PART A: MULTIPLE CHOICE Value: 60 marks Suggested … · Consider the following potential energy diagram for a ... Which of the following represents the predominant reaction ... select

OVER- 1 -

PART A: MULTIPLE CHOICE

Value: 60 marks Suggested Time: 70 minutes

INSTRUCTIONS: For each question, select the best answer and record your choice on the ResponseForm provided. Using an HB pencil, completely fill in the circle that has the lettercorresponding to your answer.

Selected multiple-choice questions are worth 2 marks.

1. Consider the following reaction: (1 mark)

N H H O N H O2 4 2 2 2 22 4l l l( ) ( ) ( ) ( )+ → +g

In 5 0. seconds, 0 015. mol of H O2 2 is consumed. The rate of production of N2 is

A. 1 5 10 3. × − mol s

B. 3 0 10 3. × − mol s

C. 6 0 10 3. × − mol s

D. 1 5 10 2. × − mol s


3 2 462 3 3 4 2Fe O CO Fe O CO kJs g s g( ) ( ) ( ) ( )+ → + +

Which of the following would cause the rate of the reaction to increase?

A. removing the Fe O3 4

B. decreasing the temperatureC. increasing the surface area of Fe O2 3

D. increasing the volume of the reaction vessel

3. Activation energy is described as (1 mark)

A. the energy of the activated complex.B. a point on the PE diagram where KE PE= .C. the unstable high PE structural arrangement of atoms.D. the minimum PE difference between the activated complex and the reactants.

- 2 -

4. What happens to the activation energy and ∆H whena catalyst is added to a reaction? (2 marks)

Activation Energy ∆H

A. increases remains the same

B. increases increases

C. decreases remains the same

D. decreases decreases

5. Consider the following potential energy diagram for a reaction: (1 mark)

Progress of the reaction

PE(kJ)

60

120

180

240

30

90

150

210

What is the value of ∆H for this reaction?

A. −120 kJ

B. −30 kJ

C. +30 kJ

D. +120 kJ

OVER- 3 -

6. A substance that is produced in one step in a reaction mechanism and consumedin a subsequent step, without appearing in the overall reaction, is a(n) (1 mark)

A. catalyst.B. product.C. reactant.D. intermediate.

7. All chemical equilibriums must have (1 mark)

A. Keq = 1

B. reactants[ ] = [ ]products .

C. rate forward rate reverse= .

D. mass of reactants mass of products.=

8. Consider the following equilibrium reaction: (2 marks)

4 2 2 111 42 2 2HCl O H O Cl kJg g g g( ) ( ) ( ) ( )+ →← + + .

For the forward reaction, how do enthalpy and entropy change?

Enthalpy Entropy

A. increases decreases

B. decreases decreases

C. increases increases

D. decreases increases

- 4 -

9. Consider the following equilibrium: (1 mark)

CH Cl OH CH OH Cl3 3aq aq aq aq( ) ( )−

( ) ( )−+ →← +

The equilibrium will shift to the left as a result of the addition of

A. HNO3

B. KNO3

C. NaOH

D. CH Cl3

10. Consider the following equilibrium at 25°C : (1 mark)

Ni CO Ni COs g( ) ( ) ( )+ →← ( )4 4 l

For this reaction

A. K COeq = [ ]4

B. KCOeq =

[ ]1

4

C. KNi CO

CO Nieq =( )[ ]

[ ] [ ]4

4

D. KNi CO

COeq =( )[ ]

[ ]4

4

OVER- 5 -


2 2 002 2 4COF CO CF Kg g g eq( ) ( ) ( )→← + = .

At equilibrium, CO mol L2 0 050[ ] = . and CF mol L4 0 050[ ] = . .

What is COF2[ ] at equilibrium?

A. 0 0012. mol L

B. 0 035. mol L

C. 0 050. mol L

D. 0 22. mol L

12. Consider the following equilibrium: (2 marks)

H O Cl O HOCl K2 2 2 0 0900g g g eq( ) ( ) ( )+ →← = .

Initially, a 1 00. L flask is filled with 0 100. mol of H O2 , 0 100 2. mol of Cl Oand 0 100. mol of HOCl. As equilibrium is established, the reaction proceeds to the

A. left because K KTrial eq>B. left because K KTrial eq<C. right because K KTrial eq>D. right because K KTrial eq<

13. At 25°C , which of the following compounds has a low solubility whenadded to water? (1 mark)

A. FeSB. CuCl2

C. ZnSO4

D. NH CH COO4 3

- 6 -

14. Which of the following forms a molecular solution? (1 mark)

A. KClB. NaOHC. CH OH3

D. NH CH COO4 3

15. List the compounds AgI KBr and MgCO, 3 in order of solubilityfrom lowest to highest. (2 marks)

A. AgI MgCO KBr, ,3

B. KBr AgI MgCO, , 3

C. KBr MgCO AgI, ,3

D. MgCO AgI KBr3, ,

16. Consider the following Ksp expression: (1 mark)

K Cu IOsp = [ ][ ]+ −23

2

Which of the following does this equilibrium expression represent?

A. CuIO Cu IO3 3s aq aq( ) ( )+

( )−→← +

B. CuIO Cu IO32

32

s aq aq( ) ( )+

( )−→← +

C. CuIO Cu IO32

3s aq aq( ) ( )+

( )−→← +

D. Cu IO Cu IO3 22

32( ) →← +( ) ( )+

( )−

s aq aq

17. The solubility of NiCO3 is 3 8 10 4. × − mol L. The Ksp value is (1 mark)

A. 1 4 10 7. × −

B. 3 8 10 4. × −

C. 7 6 10 4. × −

D. 1 9 10 2. × −

OVER- 7 -

18. The Ag+[ ] in a saturated solution of AgBrO3 is (1 mark)

A. 2 8 10 9. × − M

B. 2 6 10 5. × − M

C. 5 3 10 5. × − M

D. 7 3 10 3. × − M

19. When solutions of AgNO3 and NaCl are combined,the Trial K for AgCl issp 5 6 10 11. × − . Predict what will be observed. (2 marks)

A. a precipitate will form because Trial K Ksp sp<B. a precipitate will form because Trial K Ksp sp>C. a precipitate will not form because Trial K Ksp sp<D. a precipitate will not form because Trial K Ksp sp>

20. Calculate the maximum CO32−[ ] that can exist in a solution

without forming a precipitate when Mg M2 0 20+[ ] = . . (1 mark)

A. 1 4 10 6. × − M

B. 3 4 10 5. × − M

C. 2 6 10 3. × − M

D. 5 8 10 3. × − M

21. Which of the following reactions is not a neutralization reaction? (1 mark)

A. KOH HF KF H O+ → + 2

B. CH O CO H O4 2 2 22 2+ → +C. Ca OH HCl CaCl H O( ) + → +2 2 22 2

D. Na CO H SO Na SO CO H O2 3 2 4 2 4 2 2+ → + +

- 8 -

22. What is the conjugate acid and what is the conjugate base of HPO42− ? (2 marks)

Conjugate Acid Conjugate Base

A. PO43− H PO2 4

−

B. H PO2 4− PO4

3−

C. H PO2 4− H PO3 4

D. H PO3 4 PO43−

23. Which of the following would be the same when comparing equal volumesof 1 0. M HBr and 1 0 3. M CH COOH? (1 mark)

A. the pHB. the electrical conductivityC. the titration curve for reaction with a baseD. the moles of base required for neutralization

24. Which of the following represents the predominant reactionbetween NH3 and H O2 ? (1 mark)

A. NH H O NH O H3 2 3 2+ →← +

B. NH H O NH OH3 2 4+ →← ++ −

C. NH H O NH O3 2 52 2+ →← ++ −

D. NH H O H O NH3 2 3 2+ →← ++ −

OVER- 9 -

25. Consider the following reaction: (2 marks)

HPO H SO H PO HSO42

2 3 2 4 3− − −+ →← +

What is the strongest acid and strongest base in the above system?

Strongest acid Strongest base

A. H PO2 4− HSO3

−

B. H PO2 4− HPO4

2−

C. H SO2 3 HSO3−

D. H SO2 3 HPO42−

26. When a solution has pOH = 5 30. , the OH−[ ] is (1 mark)

A. 5 0 10 6. × − M

B. 2 0 10 9. × − M

C. 0 72. M

D. 13 27. M

27. How many moles of HI are needed to prepare 3 0. L of an HI solutionwith a pH of 1 00. ? (1 mark)

A. 0 030. molB. 0 30. molC. 3 0. molD. 30 mol

28. Which of the following 1 0 10 3. × − M solutions has a pH of 3 0. ? (1 mark)

A. HClB. HCNC. NaOHD. K SO2 4

- 10 -

29. Which of the following expressions shows the relationshipbetween K and Ka b for a conjugate pair? (1 mark)

A. K Ka b× = 14

B. K Ka b+ = 14

C. K K Ka b w× =D. K K Ka b w÷ =

30. Which of the following will be the most basic? (1 mark)

A. 1 0 3. M NO −

B. 1 0 42. M SO −

C. 1 0 32. M CO −

D. 1 0 43. M PO −

31. Dissolving NaCH COO3 in water will produce a solution which is (2 marks)

A. basic with pH > 7B. basic with pH < 7C. acidic with pH > 7D. acidic with pH < 7

32. Which would produce a yellow solution at a pH = 4 0. ? (1 mark)

A. methyl redB. methyl violetC. indigo carmineD. chlorophenol red

OVER- 11 -

33. How many moles of NaOH are required to react completelywith 100 0 2 5 3. .mL of M HNO ? (1 mark)

A. 0 0063. mol

B. 0 25. mol

C. 2 5. mol

D. 250 mol

34. The net ionic equation for the reaction between HCl and KOH is (1 mark)

A. H OH H O+ −+ →← 2

B. HCl KOH H O KCl+ →← +2

C. H Cl K OH H O KCl+ − + −+ + + →← +2

D. H Cl K OH H O K Cl+ − + − + −+ + + →← + +2

35. Which of the following titrations would have a pH > 7 at the equivalence point? (1 mark)

A. HI with KOH

B. HClO with NH4 3

C. HCl with Sr OH( )2

D. HCOOH with NaOH

36. A buffer can be made from equal moles of (2 marks)

A. HCl and NaCl

B. HCN and KOH

C. HNO and NH3 3

D. CH COOH and NaCH COO3 3

37. Which of the following dissolves in water to produce a basic solution? (1 mark)

A. O2

B. SO2

C. NO2

D. MgO

- 12 -

38. Consider the following spontaneous reaction: (1 mark)

2 3 2 32 3Al Cu Al Cus aq aq s( ) ( )+

( )+

( )+ → +

In this reaction, the oxidizing agent is

A. AlB. Cu

C. Al3+

D. Cu2+

39. Bromine has an oxidation number of +3 in (1 mark)

A. KBrOB. KBrO2

C. KBrO3

D. KBrO4

40. In an experiment, Te reacts spontaneously with Ag+ but not with Ti2+ .The relative strength of oxidizing agents from strongest to weakest is (2 marks)

A. Ag Te Ti+ + +> >4 2

B. Ag Ti Te+ + +> >2 4

C. Te Ti Ag4 2+ + +> >D. Ti Te Ag2 4+ + +> >

OVER- 13 -

41. A piece of Au does not react spontaneously with 1 0. M HCl.Which of the following statements is true? (1 mark)

A. Au is a weaker reducing agent than H2

B. Au is a stronger reducing agent than H2

C. Au is a weaker oxidizing agent than H+

D. Au is a stronger oxidizing agent than H+

42. Which two species will react spontaneously with each other at standard conditions? (1 mark)

A. Cl and Br2−

B. Zn and Al3+

C. Au and Sn2+

D. I and SO2 42−

43. What occurs when a piece of Zn is placed in 1 0 3 2. M Cu NO( ) ? (1 mark)

A. Cu decreases2+[ ]B. Zn decreases2+[ ]C. NO3

−[ ] increases

D. no change occurs

- 14 -

Use the following diagram to answer questions 44 to 46.

NiZn

1.0 M Zn NO3( )2 1.0 M Ni NO3( )2

Volts

1.0 M KNO

3

44. Which of the following diagrams represents the relationship

between Zn2+[ ] and Ni2+[ ] as the cell is in operation? (1 mark)

A.

Ni2+[ ]

Zn2+[ ]

B.

Ni2+[ ]

Zn2+[ ]

C.

Ni2+[ ]

Zn2+[ ]

D.

Ni2+[ ]

Zn2+[ ]

OVER- 15 -

45. The E° for the cell in the diagram is (1 mark)

A. −1 02. Volts

B. −0 50. Volts

C. +0 50. Volts

D. +1 02. Volts

46. Which of the following does not affect the cell potential? (1 mark)

A. Ni2+[ ]B. Zn2+[ ]C. temperature

D. surface area of the electrodes

47. What type of ions move toward each electrode in an electrolytic cell? (2 marks)

Anode Cathode

A. anions cations

B. cations anions

C. anions anions

D. cations cations

48. The electrolysis of 1 0. M NaI using inert electrodes will produce (2 marks)

A. sodium and iodine.B. sodium and oxygen.C. hydrogen and iodine.D. hydrogen and oxygen.

This is the end of the multiple-choice section.Answer the remaining questions directly in this examination booklet.

OVER- 17 -

PART B: WRITTEN RESPONSE


INSTRUCTIONS: You will be expected to communicate your knowledge and understanding ofchemical principles in a clear and logical manner.

Your steps and assumptions leading to a solution must be written in the spacesbelow the questions.

Answers must include units where appropriate and be given to the correct number ofsignificant figures.

For questions involving calculation, full marks will NOT be given for providingonly an answer.

1. Consider the following proposed reaction mechanism:

Step 1 Fe H O FeH O32 2 2 2

3+ ++ →

Step 2 FeH O FeOH HO2 23 3+ +→ +

Step 3 HO H O H O HO+ → +2 2 2 2

Step 4 FeOH HO Fe H O O32

32 2

+ ++ → + +

a) Write the overall reaction. (2 marks)

b) Define the term catalyst and identify a catalyst in the above mechanism. (2 marks)

Definition:

Catalyst:

- 18 -

2. Consider the following graph for the reaction:

H I HI2 2 2g g g( ) ( ) ( )+ →←

0.4

0.8

(mol L)

I20.2

0.6

1.0HI

t3t10

Concentration

Time

H2

t2

The temperature is increased at t1 and equilibrium is re-established at t2.

a) On the above graph, sketch the line representing the HI[ ] between time t1 and t3. (1 mark)

b) Calculate the value of Keq after t2. (2 marks)

OVER- 19 -

3. Consider the following equilibrium system:

2 22 2 3SO O SOg g g( ) ( ) ( )+ →←

A 1 00. L container is initially filled with 0 100 0 1002 2. .mol SO and mol O .At equilibrium the O2 concentration is 0 060. mol L . Calculate the value of Keq . (4 marks)

- 20 -

4. Hard water, containing Ca2+ ions, forms a precipitate with sodium stearate NaC H O18 35 2( ) .

a) Write the net ionic reaction that represents this precipitation. (2 marks)

b) Identify another compound that could be used to remove Ca2+ from hard water. (1 mark)

5. Calculate the mass of SrCO3 dissolved in 1 00. L of a saturated solution of SrCO3. (3 marks)

OVER- 21 -

6. Consider the 0 10. M solutions of the following two acids:

Acid HA

0.10 M

Acid HB

0.10 M

pH = 1.00 pH = 2.87

a) What can you conclude about the acids that will explain these different pH values? (1 mark)

You can conclude that acid HA:

You can conclude that acid HB:

b) Compare the volume of 0 10. M NaOH needed to neutralize equal volumes ofeach of these acid samples. (1 mark)

- 22 -

7. Consider a 1 0. M solution of NH F4 .

a) Write both hydrolysis reactions that occur when NH F4 is dissolved in water. (2 marks)

b) Will the above NH F4 solution be acidic, basic, or neutral?Support your answer with calculations. (2 marks)

OVER- 23 -

8. An indicator is often used during acid-base titrations.

a) Define the term transition point for an indicator. (1 mark)

b) Calculate the Ka value for methyl red. (1 mark)

c) A mixture of indicators is made by combining equal amounts of methyl orangeand bromthymol blue. Complete the following table, showing the colour of eachindicator and the mixture at pH of 5 and pH of 9. (2 marks)

pH=5

pH=9

Colour ofmethyl orange

Colour ofbromthymol blue

Colour ofmixture

9. Will HC O2 4− act predominantly as an acid or as a base in solution?

Support your answer with calculations. (3 marks)

- 24 -

10. Consider the following redox reaction in acidic solution:

MnO H O Mn O acidic4 2 22

2− ++ → + ( )

a) Write a balanced equation for the above reaction. (4 marks)

b) The above reaction was used for a redox titration. At the equivalence point5 684 10 4

4. × − mol KMnO was required to titrate 5 00 2 2. mL of H O solution.

Calculate the H O2 2[ ]. (2 marks)

- 25 -

11. Cathodic protection is one method used to inhibit the corrosion of iron.

a) Explain the principle of cathodic protection. (2 marks)

b) Identify two methods, other than cathodic protection, that could be used toinhibit the corrosion of iron. (2 marks)

i)

ii)

END OF EXAMINATION

018chk - 1 - September 7, 2001

Chemistry 12August 2001 Provincial Examination

ANSWER KEY / SCORING GUIDE

CURRICULUM:

Organizers Sub-Organizers

1. Reaction Kinetics

2. Dynamic Equilibrium

3. Solubility Equilibria

4. Acids, Bases, and Salts

5. Oxidation – Reduction

A, B, C

D, E, F

G, H, I

J, K, L, M, N, O, P, Q, R

S, T, U, V, W

Part A: Multiple Choice

Q K C S CO PLO Q K C S CO PLO

1. A U 1 1 A2 25. D U 2 4 K62. C U 1 1 A6 26. A U 1 4 L123. D K 1 1 B3 27. B U 1 4 L114. C H 2 1 C4 28. A H 1 4 L125. B U 1 1 B7 29. C K 1 4 M46. D K 1 1 C5 30. D K 1 4 M27. C K 1 2 D4 31. A U 2 4 N38. B U 2 2 D7 32. D U 1 4 O39. A H 1 2 E2; J3 33. B U 1 4 P2

10. B K 1 2 F2 34. A K 1 4 P411. B U 1 2 F5 35. D K 1 4 P612. A U 2 2 F8 36. D K 2 4 Q213. A K 1 2 H1 37. D K 1 4 R114. C U 1 3 G1 38. D U 1 5 S115. A U 2 3 H1 39. B U 1 5 S216. D K 1 3 I2 40. A U 2 5 S417. A U 1 3 I3 41. A U 1 5 S518. D U 1 3 I4 42. A K 1 5 S619. C H 2 3 I5 43. A U 1 5 T420. B H 1 3 I6 44. C H 1 5 U521. B U 1 4 J3 45. C U 1 5 U922. B U 2 4 J11 46. D K 1 5 U823. D K 1 4 K2 47. A K 2 5 W324. B U 1 4 K5 48. C U 2 5 W4

Multiple Choice = 60 marks (48 questions)


Part B: Written Response

Q B C S CO PLO

1. 1 U 4 1 C2, 3, 5

2. 2 U 3 2 E2; F4

3. 3 U 4 2 F5

4. 4 U 3 3 H3, 7

5. 5 U 3 3 H4

6. 6 H 2 4 K9; P3

7. 7 U 4 4 M2; N2

8. 8 U 4 4 O2, 5

9. 9 U 3 4 N4

10. 10 U 6 5 T2, 6

11. 11 U 4 5 V3, 4

Written Response = 40 marks

Multiple Choice = 60 (48 questions)Written Response = 40 (11 questions)

EXAMINATION TOTAL = 100 marks

LEGEND:

Q = Question Number K = Keyed Response C = Cognitive LevelB = Score Box Number S = Score CO = Curriculum OrganizerPLO = Prescribed Learning Outcome








1. Consider the following proposed reaction mechanism:

Step 1 Fe H O FeH O32 2 2 2

3+ ++ →

Step 2 FeH O FeOH HO2 23 3+ +→ +

Step 3 HO H O H O HO+ → +2 2 2 2

Step 4 FeOH HO Fe H O O32

32 2

+ ++ → + +

a) Write the overall reaction. (2 marks)

Solution:

For Example:

2 22 2 2 2H O H O O→ +

← 2 marks

b) Define the term catalyst and identify a catalyst in the above mechanism. (2 marks)

Solution:

For Example:

Definition: A species which speeds up a reaction byproviding a lower energy pathway.

Catalyst: Fe3+

← 2 marks


2. Consider the following graph for the reaction:

H I HI2 2 2g g g( ) ( ) ( )+ →←

0.4

0.8

(mol L)

I20.2

0.6

1.0HI

t3t10

Concentration

Time

H2

t2

The temperature is increased at t1 and equilibrium is re-established at t2.

a) On the above graph, sketch the line representing the HI[ ] between time t1 and t3. (1 mark)

Solution:

For Example:

See graph above.

← 1 mark

b) Calculate the value of Keq after t2. (2 marks)

Solution:

For Example:

KHI

H Ieq = [ ][ ][ ]

= ( )( )( )

=

2

2 2

21 00 5 0 1

20

.. .

← 2 marks



2 22 2 3SO O SOg g g( ) ( ) ( )+ →←

A 1 00. L container is initially filled with 0 100 0 1002 2. .mol SO and mol O .At equilibrium the O2 concentration is 0 060. mol L . Calculate the value of Keq . (4 marks)

Solution:

For Example:

2 2

0 100 0 100 0

0 080 0 040 0 080

0 020 0 060 0 080

2 2 3SO O SO

I

C

E

g g g( ) ( ) ( )+ →←

[ ]

[ ] − − +

[ ]

. .

. . .

. . .

KSO

SO Oeq = [ ]

[ ] [ ]

= ( )( ) ( )

= ×

32

22

2

2

2

2

0 080

0 020 0 060

2 7 10

.

. .

.

← 2 marks

← 2 marks


4. Hard water, containing Ca2+ ions, forms a precipitate with sodium stearate NaC H O18 35 2( ) .

a) Write the net ionic reaction that represents this precipitation. (2 marks)

Solution:

Ca C H O Ca C H Oaq aq s( )+

( )−

( )+ → ( )218 35 2 18 35 2 22 ← 2 marks

b) Identify another compound that could be used to remove Ca2+ from hard water. (1 mark)

Solution:

For Example:

Na CO2 3 ← 1 mark


5. Calculate the mass of SrCO3 dissolved in 1 00. L of a saturated solution of SrCO3. (3 marks)

Solution:

For Example:

SrCO Sr CO32

32

s aq aq( ) ( )+

( )−→← +

K Sr CO

Sr CO

sp = [ ][ ] = ×

[ ] = [ ] = ×

+ − −

+ − −

23

2 10

23

2 5

5 6 10

2 36 10

.

.

Mass of SrCO dissolved in L molg

mol

g

35

3

1 00 2 36 10147 6

3 5 10

. ..

.

= × ×

= ×

−

−

← 3 marks


6. Consider the 0 10. M solutions of the following two acids:

Acid HA

0.10 M

Acid HB

0.10 M

pH = 1.00 pH = 2.87

a) What can you conclude about the acids that will explain these different pH values? (1 mark)

Solution:

For Example:

Acid HA is strong.

Acid HB is weak.

←1 mark

b) Compare the volume of 0 10. M NaOH needed to neutralize equal volumes ofeach of these acid samples. (1 mark)

Solution:

For Example:

The same volume of NaOH aq( ) is needed for each acid

sample.

←1 mark


7. Consider a 1 0. M solution of NH F4 .

a) Write both hydrolysis reactions that occur when NH F4 is dissolved in water. (2 marks)

Solution:

For Example:

NH H O NH H O

F H O HF OH

4 2 3 3

2

aq aq aq

aq aq aq

( )+

( ) ( ) ( )+

( )−

( ) ( ) ( )−

+ →← +

+ →← +

l

l

← 1 mark

← 1 mark

b) Will the above NH F4 solution be acidic, basic, or neutral?Support your answer with calculations. (2 marks)

Solution:

For Example:

K for NH

K for FKK

Since K K the solution is acidic

a

bw

a

a b

410

14

411

5 6 10

1 0 103 5 10

2 9 10

+ −

−−

−−

= ×

= = ××

= ×

>

.

..

.

, .

← 2 marks

018chk - 10 - September 7, 2001

8. An indicator is often used during acid-base titrations.

a) Define the term transition point for an indicator. (1 mark)

Solution:

For Example:

The point where the indicator is halfwaythrough the colour change.

OR

HInd Ind[ ] = [ ]−

←1 mark

b) Calculate the Ka value for methyl red. (1 mark)

Solution:

For Example:

Average pH

K

= + =

= ×

= ×

−

−

4 8 6 02

5 4

1 10

4 10

5 4

6

. ..

.a

←1 mark

c) A mixture of indicators is made by combining equal amounts of methyl orangeand bromthymol blue. Complete the following table, showing the colour of eachindicator and the mixture at pH of 5 and pH of 9. (2 marks)

pH=5

pH=9

Colour ofmethyl orange

Colour ofbromthymol blue

Colour ofmixture

yellow yellow yellow

yellow blue green

← 2 marks

018chk - 11 - September 7, 2001

9. Will HC O2 4− act predominantly as an acid or as a base in solution?

Support your answer with calculations. (3 marks)

Solution:

For Example:

KKKb

w

a= = ×

×= ×

−

−−1 0 10

5 9 101 7 10

14

213.

..

←1 mark12 s

Since Ka = × −6 4 10 5. which is greater than Kb , the ions actas an acid.

←1 mark12 s

018chk - 12 - September 7, 2001

10. Consider the following redox reaction in acidic solution:

MnO H O Mn O acidic4 2 22

2− ++ → + ( )

a) Write a balanced equation for the above reaction. (4 marks)

Solution:

For Example:

2 8 5 4

5 2 2

2 6 5 2 8 5

42

2

2 2 2

4 2 22

2 2

× + + → +( )× → + +( )

+ + → + +

− + − +

+ −

− + +

MnO H e Mn H O

H O O H e

MnO H H O Mn H O O

← 4 marks

b) The above reaction was used for a redox titration. At the equivalence point5 684 10 4

4. × − mol KMnO was required to titrate 5 00 2 2. mL of H O solution.

Calculate the H O2 2[ ]. (2 marks)

Solution:

For Example:

mol H O mol MnOmol H O

mol MnOmol

H Omol

LM

2 24

42 2

4

3

2 2

3

5 684 105

21 421 10

1 421 100 00500

0 284

= × × = ×

[ ] = × =

− −−

−

−

. .

..

.

← 2 marks

018chk - 13 - September 7, 2001

11. Cathodic protection is one method used to inhibit the corrosion of iron.

a) Explain the principle of cathodic protection. (2 marks)

Solution:

For Example:

The process of protecting a metal from oxidation by placingit in electrical contact with another metal that is a strongerreducing agent. The protected metal becomes a cathode andthe other becomes a sacrificial anode.

← 2 marks

b) Identify two methods, other than cathodic protection, that could be used toinhibit the corrosion of iron. (2 marks)

Solution:

For Example:

Coating with paint or grease.

Keep in totally dry atmosphere.

← 1 mark

← 1 mark

END OF KEY

OVER- 1 -





1. Which of the following reactions occurs most rapidly at standard conditions? (1Êmark)

A. 2 22Fe O FeOs g s( ) ( ) ( )+ →

B. CaO C CaC COs s s g( ) ( ) ( ) ( )+ → +3 2

C. SnO CO Sn CO2 22 2s g s g( ) ( ) ( ) ( )+ → +

D. 2 23 2 4 2 4 3AgNO Na CrO Ag CrO NaNOaq aq s aq( ) ( ) ( ) ( )+ → +

2. Consider the following reaction: (1Êmark)

CaO HCl CaCl H Os aq aq( ) ( ) ( ) ( )+ → +2 2 2 l

Which of the following could be used to measure the rate of this reaction?

A. change in acidityB. change in volumeC. change in pressureD. change in total mass

3. In order for a collision between reactant particles to be successful (1Êmark)

A. a ∆H must be positive.B. the system must be closed.C. there must be sufficient KE .D. the change in KE must be less than the change in PE .

- 2 -

4. Consider the following PE diagram: (1Êmark)

Progress of the reaction

PE(kJ) I

II III

IV

The activation energy for the forward reaction is represented by

A. IB. IIC. IIID. IV

5. What is the relationship between the activation energy and the rate of a reaction? (1Êmark)

A. When the activation energy is high, the rate of reaction is fast.B. When the activation energy is low, the rate of reaction is slow.C. When the activation energy is high, the rate of reaction is slow.D. There is no relationship between activation energy and rate of reaction.

6. Consider the following reaction mechanism: (1Êmark)

Step 1 OCl H O HOCl OH− −+ → +2

Step 2 I HOCl HOI Cl− −+ → +

Step 3 HOI OH H O OI+ → +− −2

Which of the following is correct for the overall reaction?

A. HOI is a product.B. H O2 is a reactant.

C. HOCl is a catalyst.

D. OH− is a reaction intermediate.

OVER- 3 -

7. Consider the following equilibrium reaction: (2Êmarks)

2 2 2ICl I Clg g g( ) ( ) ( )→← +

Some ICl is added to an empty flask. How do the reaction rates change asthe system approaches equilibrium?

forward rate reverse rate

A. increases increases

B. increases decreases

C. decreases increases

D. decreases decreases

8. In an equilibrium system, continuing microscopic changes indicate thatthe equilibrium is (1Êmark)

A. dynamic.B. complete.C. exothermic.D. spontaneous.

9. Consider the following equilibrium: (1Êmark)

4 2 2 2CuO energy Cu O Os s g( ) ( ) ( )+ →← +

The equilibrium will shift to the right as a result of

A. adding CuO s( ).

B. removing O g2( ) .

C. adding a catalyst.

D. decreasing the temperature.

- 4 -

10. Consider the following equilibrium: (2Êmarks)

N H NH2 2 33 2g g g( ) ( ) ( )+ →←

The volume of the system is decreased. The equilibrium shifts

A. left since the reverse rate is greater than the forward rate.B. left since the forward rate is greater than the reverse rate.C. right since the reverse rate is greater than the forward rate.D. right since the forward rate is greater than the reverse rate.

11. Consider the following equilibrium: (2Êmarks)

2 2 1983 2 2SO SO O H kJg g g( ) ( ) ( )→← + = +∆

When the temperature is increased, the equilibrium will shift

A. left with Keq becoming larger.

B. right with Keq becoming larger.

C. left with Keq becoming smaller.

D. right with Keq becoming smaller.

12. Starting with equal concentrations of reactants, which of the following will beclosest to completion at equilibrium? (1Êmark)

A. CO Cl COClg g g( ) ( ) ( )+ →←2 2 Keq = 22

B. PCl Cl PCl3 2 5g g g( ) ( ) ( )+ →← Keq = × −2 9 10 2.

C. CO Cl COClg g g( ) ( ) ( )+ →←2 2 Keq = × −4 5 10 9.

D. CH O NO CH O NO3 2 2 3 2 2g g g( ) ( ) ( )+ →← Keq = × −2 1 10 12.

OVER- 5 -

13. Consider the following equilibrium: (1Êmark)

2 2 2 4COF CO CFg g g( ) ( ) ( )→← +

At equilibrium, a 1 00. L container contains 7 07 10 1 00 1042

32. , . ,× ×− −mol COF mol CO

andÊ1 00 10 34. × − mol CF . What is the value of Keq?

A. 7 07 10 4. × −

B. 1 41 10 3. × −

C. 0 500.

D. 2 00.

14. Which of the following dissolves in water to form a molecular solution? (1Êmark)

A. KClB. Na O2C. NH Br4

D. C H OH2 5

15. A saturated solution is formed by adding 10 0 10 02. .g PbI to mLs( ) of water in a beaker.

Describe the situation which exists in the beaker. (1Êmark)

A. Pb I2+ −[ ] = [ ]B. moles PbI moles Pb2

2s aq( ) ( )

+=

C. mass of P mass of PbI bI2 2s aq( ) ( )=

D. rate of crystalization rate of dissociation=

16. What is the concentration of barium ions in a 1 00. L solutioncontaining 2 08 2. g of BaCl ? (1Êmark)

A. 1 00 10 2. × − M

B. 1 21 10 2. × − M

C. 2 00 10 2. × − M

D. 2 08. M

- 6 -

17. Which of the following salts has low solubility? (1Êmark)

A. MgS

B. ZnCl2C. SrSO4D. AgNO3

18. Consider the following solubility equilibrium: (2Êmarks)

AgCl Ag Cls aq aq( ) ( )+

( )−→← +

Some NaCl s( ) is added to the equilibrium. When equilibrium is reestablished,

how have the ion concentrations changed from the original equilibrium?

Ag+[ ] Cl−[ ]A. decreased increased

B. decreased decreased

C. increased decreased

D. increased increased

OVER- 7 -

19. A precipitate forms when a 0 20. M solution containing an unknown cation

is added to SO42− , but not when an equal volume is added to S2− . (2Êmarks)

0.20 M unknown cation 0.20 M unknown cation

0.20 M SO42− 0.20 M S2−

The unknown cation is

A. Na+

B. Ca2+

C. Pb2+

D. Zn2+

20. The Ksp expression for a saturated solution of Ni PO3 4 2( ) is (1Êmark)

A. K Ni POsp = [ ] [ ]+ −2 3

43 2

B. K Ni POsp = [ ] [ ]+ −2 2

43 3

C. K Ni POsp = [ ][ ]+ −3 2243

D. K Ni POsp = [ ] [ ]+ −3 22 3

43 2

21. Which of the following are general properties of bases in aqueous solution? (2Êmarks)

A. feel slippery and increase H O3+[ ]

B. turn litmus red and accept a proton

C. conduct electricity and turn litmus blue

D. feel slippery and react with Au to produce H2 g( )

- 8 -

22. The conjugate base of H PO2 4− is (1Êmark)

A. PO43−

B. HPO4−

C. HPO42−

D. H PO3 4

23. The electrical conductivities of 0 10 2. ,M solutions of NaCl HCN and HNO are measured.The order by conductivity from highest to lowest is (2Êmarks)

A. NaCl HNO HCN> >2

B. HCN HNO NaCl> >2

C. NaCl HCN HNO> > 2

D. HNO HCN NaCl2 > >

24. Which of the following acids has the weakest conjugate base? (1Êmark)

A. HIO3B. HNO2C. H PO3 4

D. CH COOH3

25. When 10 0 0 10. .mL of M HCl is added to 10 0. mL of water, the concentration

ofÊH O3+ in the final solution is (1Êmark)

A. 0 010. M

B. 0 050. M

C. 0 10. M

D. 0 20. M

OVER- 9 -

26. Which of the following chemical species are amphiprotic in aqueous solution? (2Êmarks)

I. F−

II. NH4+

III. HPO42−

A. I only.B. II only.C. III only.D. II and III only.

27. A solution is prepared by mixing 1 50 10 3. × − mol HCl with 3 00 10 3. × − mol KOH .

Calculate the moles of OH− present after mixing. (1Êmark)

A. 0 mol

B. 1 50 10 3. × − mol

C. 3 00 10 3. × − mol

D. 4 50 10 3. × − mol

28. Calculate the pH in a 0 020. M solution of Sr OH( )2 . (2Êmarks)

A. 1 40.B. 1 70.C. 12 30.D. 12 60.

29. The Kb value for HPO42− is (1Êmark)

A. 2 2 10 13. × −

B. 6 2 10 8. × −

C. 1 6 10 7. × −

D. 7 5 10 3. × −

- 10 -

30. Which of the following 1 0. M salt solutions is acidic? (1Êmark)

A. BaSB. NH Cl4

C. Ca NO3 2( )D. NaCH COO3

31. Which of the following represents the hydrolysis reaction that occursin a solution of K C O2 2 4 ? (1Êmark)

A. K C O K C O2 2 4 2 422→← ++ −

B. K H O KOH H O+ ++ →← +2 2 3

C. C O H O HC O OH2 42

2 2 4− − −+ →← +

D. K C O H O K CO CO H2 2 4 2 2 3 2 2+ →← + +

32. When the indicator thymol blue is added to a 0 10. M solution of an unknown acid,the solution is red. The acid could be (1Êmark)

A. HFB. H S2C. HCND. HNO3

OVER- 11 -

33. The complete neutralization of 15 0. mL of KOH requires 0 025 2 4. mol H SO .TheÊ KOH[ ]Êwas (1Êmark)

A. 1 50. M

B. 1 67. M

C. 3 33. M

D. 6 67. M

34. What is the H O3+[ ] at the equivalence point for the titration

between HBr and KOH ? (1Êmark)

A. 1 0 10 9. × − M

B. 1 0 10 7. × − M

C. 1 0 10 5. × − M

D. 0 0. M

35. Which of the following would form a buffer solution when equal molesare mixed together? (1Êmark)

A. HCl and NaCl

B. HCN and NaCN

C. KNO and KOH3

D. Na SO and NaOH2 4

36. Which of the following oxides dissolves to form a solution with a pH greater than 7 ? (1Êmark)

A. SO2B. CO2C. N O2D. K O2

- 12 -

37. The pH of acid rain could be (1Êmark)

A. 5 0.B. 7 0.C. 9 0.D. 11 0.

38. Consider the following reaction: (1Êmark)

Zn H Zn Hs aq aq g( ) ( )+

( )+

( )+ → +2 22

The species being oxidized is

A. H2B. H+

C. Zn

D. Zn2+

39. When SO reacts to form S O42

2 62− − , the sulphur atoms (2Êmarks)

A. lose electrons and are reduced.B. gain electrons and are reduced.C. lose electrons and are oxidized.D. gain electrons and are oxidized.

40. Which of the following is a list of metals in order from strongest to weakestreducing agents? (1Êmark)

A. Au Ni Rb> >B. Ni Au Rb> >C. Ni Rb Au> >D. Rb Ni Au> >

OVER- 13 -

41. Consider the following spontaneous reaction:

Mg HCl MgCl Hs aq aq g( ) ( ) ( ) ( )+ → +2 2 2

Which of the following statements is correct? (1Êmark)

A. Mg is a weaker reducing agent than H2

B. Mg is a weaker reducing agent than H+

C. Mg is a stronger reducing agent than H2

D. Mg is a stronger reducing agent than H+

42. Which of the following will not react spontaneously with H O2at standard conditions? (1Êmark)

A. F2B. Ca

C. Na

D. Sn

43. When a piece of Cu is placed in 1 0 3. M AgNO , (1Êmark)

A. the Ag+[ ] increases.

B. the Cu2+[ ] increases.

C. the NO3−[ ] decreases.

D. no change occurs.

- 14 -

Use the following diagram to answer questions 44 and 45.

NiCu

1.0 M Cu NO3( )2 1.0 M Ni NO3( )2

Volts

1.0 M KNO

344. Which of the following diagrams represents the relationship between Ni2+[ ] and

the mass of the Cu electrode as the cell above is in operation? (1Êmark)

A.

Ni2+[ ]

Mass of Cu

B.

Ni2+[ ]

Mass of Cu

C.

Ni2+[ ]

Mass of Cu

D.

Ni2+[ ]

Mass of Cu

45. The E° for the above cell is (1Êmark)

A. −0 04. volts

B. −0 60. volts

C. +0 04. voltsD. +0 60. volts

OVER- 15 -

46. Which of the following describes an electrochemical cell? (2Êmarks)

E°cell Type of reaction

A. positive spontaneous

B. positive non-spontaneous

C. negative spontaneous

D. negative non-spontaneous

47. Which of the following aqueous solutions should not be used as an electrolytein an electrolytic cell? (1Êmark)

A. 1 0. M KOH

B. 1 0 2 4. M H SO

C. 1 0 4. M CuSO

D. 1 0 6 12 6. M C H O

48. When 1 0 2 4. M Na SO is electrolyzed, the solution near the anode becomes (2Êmarks)

A. basic and bubbles form.B. acidic and bubbles form.C. basic and no bubbles form.D. acidic and no bubbles form.


- 16 -







1. An Alka-Seltzer tablet is added to water to produce carbon dioxide gas. The gas was collectedusing water displacement.

0

3.0

20.0

33.5

43.0

43.0

43.0

The following data is recorded:

Time (s) Volume of CO2 (mL)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

OVER- 17 -

a) Calculate the average rate of reaction for the formation of CO2 gas for the times:

i) 0 10− s (1Êmark)

ii) 10 20− s (1Êmark)

b) Suggest a reason why the rate of reaction from 0 10 0to s. is slower than the ratefrom 10 0 20 0. .to s ? (1Êmark)

c) The rate of reaction is not constant during the entire interval from 10 0 40 0. .to s.Describe the change in rate and explain a reason for the change. (2Êmarks)

- 18 -

2. A flask is initially filled with some HI . At equilibrium, the HI mol L[ ] = 0 80. .

What is the H2[ ] at equilibrium? (3Êmarks)

2 0 252 2HI H I Kg g g eq( ) ( ) ( )→← + = .

OVER- 19 -


2 2 1 6 1025NOCl NO Cl Kg g g eq( ) ( ) ( )

−→← + = ×.

A 1 00. L flask is filled with 0 20. ,mol NOCl 0 10. mol NO and 0 10 2. mol Cl .

State and show by calculation the direction in which the reaction proceeds to

reach equilibrium. (4Êmarks)

Direction:

Calculations:

- 20 -

4. In a titration, 25 00. mL of NaCl aq( ) reacts completely with 42 20. mL of 0 100 3. M AgNO .

What is the Cl−[ ] in the original solution? (3Êmarks)

OVER- 21 -

5. The following data was obtained when 20 0. mL of a saturated solution of PbI2 was evaporatedto dryness.

Mass of evaporating dish 30 250. g

Mass of evaporating dish and residue 30 262. g

Use this information to determine the K of PbIsp 2 . (4Êmarks)

- 22 -

6. a) Write the equation for the predominant reaction of HC O2 4− with HSO3

− . (1Êmark)

HC O HSO

acid base

2 4 3− −+ →← +

b) Identify a Br¿nsted-Lowry conjugate acid base pair from the above reaction. (1Êmark)

Acid: Base:

7. a) In the space below, sketch the titration curve for the reactionwhenÊ0 10 10 0 0 10. . .M HCl is added to mL of M NaOH . (3Êmarks)

2

14

468

1012

0

pH

Volume of added HCl (mL)

5.0 10.0 15.0 20.0

b) Describe two changes in the titration curve that would result fromusing 0 10 3. M CH COOH in place of the HCl . (2Êmarks)

i)

ii)

OVER- 23 -

8. Calculate the OH in M NH−( )[ ] 0 50 3. aq . (5Êmarks)

- 24 -

9. Balance the following redox reaction in basic solution. (5Êmarks)

MnO C O MnO CO basic4 2 42

2 32− − −+ → + ( )

- 25 -

10. a) Draw and label the parts of an operating electrolytic cell during the electrolysisof molten potassium chloride

KCl l( ). (3Êmarks)

b) Define the term oxidizing agent. (1Êmark)

END OF EXAMINATION

014chk - 1 - May 8, 2001

Chemistry 12April 2001 Provincial Examination


CURRICULUM:


1. Reaction Kinetics2. Dynamic Equilibrium3. Solubility Equilibria4. Acids, Bases, and Salts5. Oxidation Ð Reduction

A, B, CD, E, FG, H, IJ, K, L, M, N, O, P, Q, RS, T, U, V, W



1. D K 1 1 A1 25. B U 1 4 K92. A U 1 1 A4 26. C U 2 4 K113. C K 1 1 B1 27. B U 1 4 L114. B U 1 1 B6 28. D U 2 4 L125. C U 1 1 B4 29. C U 1 4 M46. D H 1 1 C5 30. B U 1 4 N37. C U 1 2 D3 31. C U 1 4 N28. A K 2 2 D5 32. D H 1 4 O3; K69. B U 1 2 E2 33. C U 1 4 P2

10. D U 2 2 E2, 3 34. B K 1 4 P1, 511. B H 2 2 F4 35. B U 1 4 Q212. A K 1 2 F3 36. D K 1 4 R113. D U 1 2 F6 37. A K 1 4 R214. D K 1 3 G1 38. C U 1 5 S115. D K 1 3 G2 39. B U 2 5 S316. A U 1 3 G8 40. D U 1 5 S517. C U 1 3 H1 41. C H 1 5 S518. A H 2 3 H5 42. D U 1 5 S619. B U 2 3 H6 43. B U 1 5 T420. A K 1 3 I2 44. A H 1 5 U521. C K 2 4 J2 45. D K 1 5 U922. C U 1 4 J11 46. A K 2 5 U1023. A H 2 4 K1, 6 47. D K 1 5 W224. A K 1 4 K6 48. B U 2 5 W4


014chk - 2 - May 8, 2001


Q B C S CO PLO

1. 1 U 5 1 A32. 2 U 3 2 F73. 3 U 4 2 F8; D64. 4 U 3 3 I75. 5 U 4 3 G5; I36. 6 U 2 4 J77. 7 U 5 4 P1, 68. 8 U 5 4 M39. 9 U 5 5 T2

10. 10 U 4 5 W8




LEGEND:Q = Question Number K = Keyed Response C = Cognitive LevelB = Score Box Number S = Score CO = Curriculum OrganizerPLO =Ê Prescribed Learning Outcome

014chk - 3 - May 8, 2001







1. An Alka-Seltzer tablet is added to water to produce carbon dioxide gas. The gas was collectedusing water displacement.

0

3.0

20.0

33.5

43.0

43.0

43.0

The following data is recorded:

Time (s) Volume of CO2 (mL)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

014chk - 4 - May 8, 2001

a) Calculate the average rate of reaction for the formation of CO2 gas for the times:

i) 0 10− s (1Êmark)

Solution:

ratevolt

mL mLs

mLs

mL s

= = −

= =

∆∆

3 0 0 010 0

3 010 0

0 30

. ..

..

. ← 1 mark

ii) 10 20− s (1Êmark)

Solution:

ratevolt

mL mLs s

mLs

mL s

= = −−

=

=

∆∆

20 0 3 020 0 10 0

17 010 0

1 70

. .. .

..

. ← 1 mark

b) Suggest a reason why the rate of reaction from 0 10 0to s. is slower than the ratefrom 10 0 20 0. .to s ? (1Êmark)

Solution:

For Example:

The surface area of the tablet increases as the tablet crumbles. ← 1 mark

c) The rate of reaction is not constant during the entire interval from 10 0 40 0. .to s.Describe the change in rate and explain a reason for the change. (2Êmarks)

Solution:

For Example:

The rate decreases during the interval becausethe surface area decreases.

← 2 marks

014chk - 5 - May 8, 2001

2. A flask is initially filled with some HI . At equilibrium, the HI mol L[ ] = 0 80. .

What is the H2[ ] at equilibrium? (3Êmarks)

2 0 252 2HI H I Kg g g eq( ) ( ) ( )→← + = .

Solution:

For Example:

KH I

HI

H M

eq =

x x

x

2 22

2

2

0 250 80

0 40

0 40

[ ][ ][ ]

←

= ( )( )( ) ←

= ←

[ ] =

1 mark

1 mark

1 mark

..

.

.

014chk - 6 - May 8, 2001


2 2 1 6 1025NOCl NO Cl Kg g g eq( ) ( ) ( )

−→← + = ×.

A 1 00. L flask is filled with 0 20. ,mol NOCl 0 10. mol NO and 0 10 2. mol Cl .

State and show by calculation the direction in which the reaction proceeds to

reach equilibrium. (4Êmarks)

Solution:

For Example:

Direction: Reaction proceeds to the left. ← 1 mark

Calculations:

2 2 2NOCl NO Clg g g( ) ( ) ( )→← +

KNO Cl

NOCl

K K

Trial

Trial eq

= [ ] [ ][ ]

= ( ) ( )( )

=

>

222

2

20 10 0 10

0 20

0 025

. .

.

.

← 1 mark

← 1 mark

← 1 mark

014chk - 7 - May 8, 2001

4. In a titration, 25 00. mL of NaCl aq( ) reacts completely with 42 20. mL of 0 100 3. M AgNO .

What is the Cl−[ ] in the original solution? (3Êmarks)

Solution:

Ag Cl AgCl

mol Ag mol L L

mol

mol Cl mol Ag

ClmolL

M

aq aq s( )+

( )−

( )

+

− +

−

+ →

= ( )( )=

=

[ ] =

=

0 100 0 04220

0 00422

0 004220 02500

0 169

. .

.

..

.

← 1 mark

← 1 mark

← 1 mark

Deduct 12 mark for incorrect significant figures.( )

014chk - 8 - May 8, 2001

5. The following data was obtained when 20 0. mL of a saturated solution of PbI2 was evaporatedto dryness.

Mass of evaporating dish 30 250. g

Mass of evaporating dish and residue 30 262. g

Use this information to determine the K of PbIsp 2 . (4Êmarks)

Solution:

For Example:

Mass of PbI g g g

Moles PbI gmol

gmol

PbmolL

M

Imol

LM

K Pb I

2

25

25

3

53

2 2

30 262 30 250 0 012

0 0121461 0

2 60 10

2 60 100 0200

1 3 10

2 2 60 100 0200

2 6 10

1

= − =

= × = ×

[ ] = × = ×

[ ] = × × = ×

= [ ] [ ] =

−

+−

−

−−

−

+ −

. . .

..

.

..

.

..

.

.sp 33 10 2 6 10 8 8 103 3 2 9×( ) ×( ) = ×− − −. .

← 12 mark

← 12 mark

← 1 mark

← 1 mark

← 1 mark

014chk - 9 - May 8, 2001

6. a) Write the equation for the predominant reaction of HC O2 4− with HSO3

− . (1Êmark)

Solution:

HC O HSO C O H SO

base acid

2 4 3 2 42

2 3− − −+ →← +

← 1 mark

b) Identify a Br¿nsted-Lowry conjugate acid base pair from the above reaction. (1Êmark)

Solution:

HC O C O

acid base

HSO H SO

base acid

2 4 2 42

3 2 3

− −

−

←OR 1 mark

014chk - 10 - May 8, 2001

7. a) In the space below, sketch the titration curve for the reactionwhenÊ0 10 10 0 0 10. . .M HCl is added to mL of M NaOH . (3Êmarks)

1 mark for general shape1 mark for showing curve drop1 mark for location of equivalence point

2

14

468

1012

0

pH

Volume of added HCl (mL)

5.0 10.0 15.0 20.0

Solution:

For Example:

See graph above. ← 3 marks

b) Describe two changes in the titration curve that would result fromusing 0 10 3. M CH COOH in place of the HCl . (2Êmarks)

Solution:

For Example:

Any two of the following for 1 mark each.

The equivalence point is > 7 .The vertical part of the curve is shorter.Buffer region.

014chk - 11 - May 8, 2001

8. Calculate the OH in M NH−( )[ ] 0 50 3. aq . (5Êmarks)

Solution:

For Example:

KKKb

w

a= = ×

×= ×

−

−−1 0 10

5 6 101 79 10

14

105.

..

NH H O NH OH

I

C

E

3 2 4

0 50 0 0

0 50

+ →← +

[ ]

[ ] −

[ ] −

+ −

.

.

x +x +x

x x x

KNH OH

NH

Use assumption that or use the quadratic formula

OH M

bx x

x

x .

x

=[ ][ ]

[ ] = ( )( )−( ) = ×

− ≈

= [ ] = ×

+ −−

− −

4

3

5

3

0 501 79 10

0 50 0 50

3 0 10

..

.

.

.

ÊÊÊÊÊ ← 1 mark

← 2 marks

← 2 marks


014chk - 12 - May 8, 2001

9. Balance the following redox reaction in basic solution. (5Êmarks)

MnO C O MnO CO basic4 2 42

2 32− − −+ → + ( )

Solution:

For Example:

2 3 4 2

3 2 2 4 2

2 2 3 2 6 4

4 2 3 2 6 2

4 2 2

2 2 42

32

2 4 2 42

2 32

4 2 42

2 32

2

× + + → +( )× + → + +( )

+ + → + +

+ + → + +

− + −

− − + −

− − − +

− − − −

e H MnO MnO H O

H O C O CO H e

H O MnO C O MnO CO H

OH MnO C O MnO CO H O

2 marks (1 mark for each half cell)

1 mark for multiplication

1 mark for addition

1 mark for basic

014chk - 13 - May 8, 2001

10. a) Draw and label the parts of an operating electrolytic cell during the electrolysisof molten potassium chloride

KCl l( ). (3Êmarks)

Solution:

For Example:

DCPowerSource

+ Ð

Anode Cathode

ClÐK+

1 mark for single container1 mark for power supply1 mark for electrodes

b) Define the term oxidizing agent. (1Êmark)

Solution:

For Example:

An oxidizing agent is a species which causes another to lose electrons. ← 1 mark

END OF KEY

OVER- 1 -





1. Which of the following reactions is slowest at room temperature? (1 mark)

A. NH HCl NH Cl3 4g g s( ) ( ) ( )+ →

B. MgCl Ca Mg CaCl2 2s s s s( ) ( ) ( ) ( )+ → +

C. HCl NaOH NaCl H Oaq aq aq( ) ( ) ( ) ( )+ → + 2 l

D. Ba NO Na SO BaSO NaNO3 2 2 4 4 32( ) + → +( ) ( ) ( ) ( )aq aq s aq


COCl CO Cl2 2g g g( ) ( ) ( )→ +

Which of the following could be used to determine reaction rate in a closed system?

A. a decrease in gas pressureB. an increase in gas pressureC. a decrease in the mass of the systemD. an increase in the mass of the system

3. Activation energy is defined as the (1 mark)

A. ∆H.B. average kinetic energy.C. energy of a particle’s motion.D. minimum energy needed for a successful collision.

4. Which of the following reactions is endothermic? (1 mark)

A. CH O CO H O kJ4 2 2 22 2 890 3g g g( ) ( ) ( ) ( )+ → + +l .

B. 2 2 287 0 42 2 2 2Na O H O kJ NaOH Os aq g( ) ( ) ( ) ( )+ − → +l .

C. CaO H O Ca OHs aq( ) ( ) ( )+ → ( )2 2l ∆H kJ= −65 2.

D. CaO C CaC COs s s g( ) ( ) ( ) ( )+ → +3 2 ∆H kJ= +464 8.

- 2 -

5. The following diagram shows reactant molecules approaching one another: (2 marks)

ClCl

O

ON

What is happening to the kinetic energy and the potential energy?

Kinetic Energy Potential Energy

A. decreasing decreasing

B. decreasing increasing

C. increasing increasing

D. increasing decreasing

6. A proposed mechanism for a reaction is: (1 mark)

Step 1 H O I HI H O3 2+ −+ → +

Step 2 H O HI H O HOI2 2 2+ → +

Step 3 HOI H O I H O I+ + → ++ −3 2 22

Step 4 I I I2 3+ →− −

In the above mechanism, which of the following is true for the overall reaction?

A. HI is a catalyst

B. H O3+ is a product

C. H O2 2 is a reactant

D. H O2 is an intermediate

OVER- 3 -

7. Consider the following reaction: (2 marks)

2 2 2ICl I Clg g g( ) ( ) ( )→← +

A closed container is initially filled with ICl g( ). What are the changes in therate of the forward reaction and I2[ ], as the system approaches equilibrium?

Rate of forwardreaction

I2[ ]

A. decreases increases

B. decreases decreases

C. increases increases

D. increases decreases

8. The entropy of a system is a term used to describe (1 mark)

A. randomness.B. heat content.C. average kinetic energy.D. stored chemical energy.


Cu Br energy CuBraq aq aq( )+

( )−

( )−+ + →←

24

24

blue colourless green

Which of the following will cause this equilibrium to change from blue to green?

A. adding NaBr s( )

B. adding NaNO3 s( )

C. adding a catalyst

D. decreasing the temperature

- 4 -


Ni CO Ni CO H kJs g( ) ( ) ( )+ →← ( ) = −4 160 84 l ∆ .

Which of the following will cause this equilibrium to shift to the left?

A. add some CO

B. decrease the volumeC. remove some Ni CO( )4

D. increase the temperature


N O energy NO2 4 22g g( ) ( )+ →←

Which of the following shows the relationship between concentration and timeas a result of adding a catalyst at time t= 1?

A.

timet1

NO2

N 2O4concentration

B.

timet1

NO2

N 2O4concentration

C.

timet1

NO2

N 2O4concentration

D.

timet1

NO2

N 2O4concentration

OVER- 5 -


H S I HI S2 2 2g s g s( ) ( ) ( ) ( )+ →← +

What is the equilibrium expression for this reaction?

A. KHIH Seq = [ ]

[ ]2

2

B. KH S

HIeq = [ ][ ]

22

C. KHI S

H S Ieq = [ ] [ ][ ][ ]

2

2 2

D. KH S I

HI Seq = [ ][ ][ ] [ ]

2 22


CO H O CO H Kg g g g eq( ) ( ) ( ) ( )+ →← + =2 2 2 5 0.

At equilibrium, the CO mol L[ ] = 0 20. , H O mol L2 0 30[ ] = . , and H mol L2 0 90[ ] = . .

Calculate the equilibrium CO2[ ].

A. 0 013. mol L

B. 0 066. mol L

C. 0 33. mol L

D. 1 0. mol L

- 6 -

14. Consider the following: (2 marks)

CO CF COF K2 4 22 0 50g g g eq( ) ( ) ( )+ →← = .

In a reaction container the initial concentrations are:

CO mol L CF mol L COF mol L2 4 20 50 0 50 0 30[ ] = [ ] = [ ] =. , . , .

To reach equilibrium, the reaction will proceed

A. left since Trial K Keq eq<B. left since Trial K Keq eq>C. right since Trial K Keq eq<D. right since Trial K Keq eq>


BaSO Ba SO42

42

s aq aq( ) ( )+

( )−→← +

Adding which of the following will cause more solid BaSO4 to form?

A. CaCl2 s( )

B. K CO2 3 s( )

C. Na SO2 4 s( )

D. Mg NO3 2( ) ( )s

16. Which of the following could not be used to represent solubility? (1 mark)

A. g mL

B. mL L

C. mol L

D. g min

OVER- 7 -

17. The following three beakers each contain different volumes ofa saturated solution of PbI2 and different masses of solid PbI2 : (2 marks)

Beaker I Beaker II Beaker III

What is the relationship for the Pb2+[ ] in the solution in the three beakers?

A. I II III= =B. I II III> >C. II III I> >D. III II I> >

18. The equation that describes the solubility equilibrium of Ag CrO2 4 is (1 mark)

A. Ag CrO Ag CrO2 4 22

42

s aq aq( ) ( )+

( )−→← +

B. Ag CrO Ag CrO2 4 422s aq aq( ) ( )

+( )−→← +

C. Ag CrO Ag Cr O2 4 22 2s s s g( ) ( ) ( ) ( )→← + +

D. Ag CrO Ag Cr O2 46 22 4s aq aq aq( ) ( )

+( )+

( )−→← + +

- 8 -

19. When 10 0 0 20 3 2. .mL of M Zn NO( ) is added to a 10 0 0 20. .mL sample of M unknown

solution, no precipitate forms. When the same volume of 0 20 3 2. M Ca NO( ) is added to a

separate 10 0. mL sample of the unknown solution, a precipitate does form. (2 marks)

no precipitateforms

0.20 M Zn NO3( )2

precipitateforms

0.20 M Ca NO3( )2

The identity of the unknown solution could be

A. NaClB. Na S2

C. Na SO2 4

D. Na CO2 3

20. The solubility of PbS is 1 8 10 14. × − M. The value of Ksp is (1 mark)

A. 3 2 10 28. × −

B. 1 8 10 14. × −

C. 3 6 10 14. × −

D. 1 3 10 7. × −

OVER- 9 -

21. A hydronium ion has the formula (1 mark)

A. H2+

B. OH−

C. H O2+

D. H O3+

22. The conjugate acid of C H NH6 5 2 is (1 mark)

A. C H NH6 5−

B. C H NH6 5 3

C. C H NH6 5 2+

D. C H NH6 5 3+

23. Which of the following is a property of 1 0. M HCl but not a propertyof 1 0 3. M CH COOH ? (1 mark)

A. turns litmus red

B. ionizes completely

C. has a pH less than 7 0.

D. produces H O3+ in solution

24. In a 1 0. M HF solution, the concentration of HF F and OH, ,− − ,from highest to lowest is (2 marks)

A. HF F OH[ ] > [ ] > [ ]− −

B. F HF OH− −[ ] > [ ] > [ ]C. OH HF F− −[ ] > [ ] > [ ]D. OH F HF− −[ ] > [ ] > [ ]

- 10 -

25. In which of the following reactions is water behaving as a Brønsted-Lowry acid? (1 mark)

A. 2 22 2 2H O H O→ +B. HCl H O H O Cl+ → ++ −

2 3

C. NH H O NH OH3 2 4+ → ++ −

D. NH H O H O NH4 2 3 3+ ++ → +

26. What is the OH−[ ] of a solution with H O M329 3 10+ −[ ] = ×. ? (1 mark)

A. 9 3. × 10 16− M

B. 8 6. × 10 13− M

C. 1 1. × 10 13− M

D. 9 3. × 10 2− M

27. The pH of M HNO0 10 3. is (1 mark)

A. 0 79.B. 1 00.C. 1 26.D. 13 00.

28. What is the pOH of a solution made by adding 50 0 0 50. .mL of M NaOHto 250 0. mL of water? (2 marks)

A. 0 30.B. 1 00.C. 1 08.D. 12 92.

29. Which of the following 1 0. M solutions will have the lowest pH? (1 mark)

A. HClB. HCNC. H PO3 4

D. H C O2 2 4

OVER- 11 -

30. The value of Kb for HTe− is 4 8 10 7. × − . The value of K for H Tea 2 is (1 mark)

A. 4 8 10 21. × −

B. 2 3 10 13. × −

C. 2 1 10 8. × −

D. 4 8 10 7. × −

31. In an aqueous solution of NaCl, the pH is (1 mark)

A. less than 7 and the solution is acidic.B. equal to 7 and the solution is neutral.C. greater than 7 and the solution is basic.D. greater than 7 and the solution is acidic.

Use the following equation for questions 32 and 33.

Consider the following equation for the indicator methyl red, HInd .

HInd H O H O Ind+ →← ++ −2 3

32. At pH = 4 0. , methyl red solution will be (2 marks)

A. red and HInd Ind[ ] > [ ]−

B. red and HInd Ind[ ] < [ ]−

C. yellow and HInd Ind[ ] > [ ]−

D. yellow and HInd Ind[ ] < [ ]−

33. Methyl red is orange in a 0 10. M solution of an acid. The acid could be (1 mark)

A. HIB. HClC. HCND. H SO2 4

- 12 -

34. How many moles of KOH are necessary to completelyneutralize 42 0. mL of 3 00. M HCl? (1 mark)

A. 0 0630. moles

B. 0 126. moles

C. 0 252. moles

D. 3 00. moles

35. At the equivalence point, the titration of HCl with NH3 willform a solution which is (2 marks)

A. basic with pH > 7.B. acidic with pH < 7.C. acidic with pH > 7.D. neutral with pH = 7.

36. Which of the following could be added to an equal number of molesof NaCH COO3 to prepare a buffer solution? (1 mark)

A. HClB. HNO3

C. NaOHD. CH COOH3

37. Which of the following equations describes the reaction that occurswhen MgO is added to water? (1 mark)

A. MgO H O Mg OH+ → ( )2 2

B. MgO H O MgO H+ → +2 2 2

C. MgO H O MgH O+ → +2 2 2

D. 2 2 22 2 2MgO H O MgOH H O+ → + +

38. Which of the following represents a redox reaction? (1 mark)

A. H I HI2 2 2+ →

B. HCl NH NH Cl+ →3 4

C. H O CO H CO2 2 2 3+ →

D. 2 23 2 2 3NaI Pb NO PbI NaNO+ ( ) → +

OVER- 13 -

39. In an experiment, Ag+ reacts spontaneously with Ru but not with Pd .The relative strength of the metals from strongest to weakest reducing agent is (2 marks)

A. Ag Ru Pd> >B. Pd Ag Ru> >C. Ru Ag Pd> >D. Ru Pd Ag> >

40. A piece of Ag does not react spontaneously with 1 0 2. M Ti + because (1 mark)

A. Ag+ is a weaker reducing agent than Ti2+

B. Ag+ is a weaker oxidizing agent than Ti2+

C. Ag+ is a stronger reducing agent than Ti2+

D. Ag+ is a stronger oxidizing agent than Ti2+

41. Which of the following will react spontaneously with Ag S2 at standard conditions? (1 mark)

A. AlB. AuC. CoD. Pb

42. When a piece of Cu is placed in 1 0 3. M HNO , (1 mark)

A. the H+[ ] increases.

B. the Cu2+[ ] decreases.

C. the NO3−[ ] decreases.

D. no change occurs.

43. When MnO2 changes to Mn O2 3 in an alkaline battery, manganese atoms (2 marks)

A. lose electrons and are reduced.B. gain electrons and are reduced.C. lose electrons and are oxidized.D. gain electrons and are oxidized.

- 14 -

Use the following cell to answer questions 44 and 45.

AgCu

1.0 M Cu NO3( )2

Volts

1.0 M KNO

3

1.0 M AgNO3

44. Which of the following diagrams represents the relationship between the mass ofthe Cu electrode and the mass of the Ag electrode as the cell is in operation? (1 mark)

A.

Mass of Ag

Massof Cu

B.

Mass of Ag

Massof Cu

C.

Mass of Ag

Massof Cu

D.

Mass of Ag

Massof Cu

45. The E° for the above cell is (1 mark)

A. −1 14. Volts

B. −0 46. Volts

C. +0 46. Volts

D. +1 14. Volts

OVER- 15 -

46. The value of E° for a cell can be used to determine (1 mark)

A. rate.B. spontaneity.C. temperature.D. activation energy.

47. How is the formation of rust on an iron can inhibited by a tin coating? (1 mark)

A. The tin is a sacrificial anode.B. The tin cathodically protects the iron.C. The tin is a weaker reducing agent than iron.D. The tin keeps the oxygen away from the iron.

48. The electrolysis of 1 0 2. M CuF using inert electrodes will produce (2 marks)

A. copper and oxygen.B. copper and fluorine.C. hydrogen and oxygen.D. hydrogen and fluorine.


- 16 -







1. The mass of a burning candle is monitored to determine the rate of combustion of paraffin.An accepted reaction for the combustion of paraffin is:

2 85 56 5828 58 2 2 2C H O CO H Os g g g( ) ( ) ( ) ( )+ → +

The following data is observed:

Time(min)

Mass of Candle(g)

0.0

6.0

12.0

18.0

24.0

30.0

25.6

25.1

24.5

23.9

23.4

22.8

OVER- 17 -

a) Calculate the average rate of consumption of paraffin in g min for thetime interval 12 0. to 24 0. minutes. (2 marks)

b) Calculate the rate of CO2 production in mol min for the timeinterval 12 0. to 24 0. minutes. (2 marks)

2. Write four statements that apply to all chemical equilibrium systems. (2 marks)

i)

ii)

iii)

iv)

- 18 -


H Br HBr K2 2 2 14 8g g g eq( ) ( ) ( )+ →← = .

A closed container was initially filled with equal moles of H2 and Br2 .

When equilibrium is reached, the HBr[ ] is 0 329. mol L . What was the initial H2[ ] ?(4 marks)

OVER- 19 -

4. Calculate the molar solubility of SrF2. (4 marks)

5. Does a precipitate form when 3 0. mL of 1 0 10 3. × − M NaBr is added

to 2 0 1 0 10 33 2. .mL of M Pb NO× ( )− ? (4 marks)

- 20 -

6. Write the equation for the predominant reaction between HSO4− and H PO2 4

− .(2 marks)

7. A 0 20. M solution of a weak acid, HA, has a pH = 1 32. .Use calculations and the table of “Relative Strengths of Brønsted-Lowry Acidsand Bases” from the Data Booklet to determine the identity of the acid. (5 marks)

The acid is:

OVER- 21 -

8. Calculate the pH of a solution prepared by mixing 15 0. mL of 0 50. M HClwith 35 0. mL of 1 0. M NaOH. (4 marks)

9. Identify a gas which causes acid rain, and write an equation showingthis gas reacting with water. (2 marks)

- 22 -

10. Balance the following redox reaction in acidic solution. (3 marks)

MnO Fe Mn Fe acidic42 2 3− + + ++ → + ( )

11. Aluminum is a stronger reducing agent than copper. What is meant by theterm stronger reducing agent? (2 marks)

- 23 -

12. Consider the electrolysis of water.

a) Draw and label the parts of an electrolytic cell capable of decomposing water. (3 marks)

b) Identify the gas produced at the anode. (1 mark)

END OF EXAMINATION

016chk - 1 - July 30, 2001

Chemistry 12June 2001 Provincial Examination


CURRICULUM:


1. Reaction Kinetics

2. Dynamic Equilibrium

3. Solubility Equilibria

4. Acids, Bases, and Salts

5. Oxidation – Reduction

A, B, C

D, E, F

G, H, I

J, K, L, M, N, O, P, Q, R

S, T, U, V, W



1. B U 1 1 A1 25. C K 1 4 K122. B U 1 1 A4 26. C U 1 4 L73. D K 1 1 B3 27. B U 1 4 L114. D K 1 1 B8 28. C U 2 4 L125. B U 2 1 B5 29. A K 1 4 M26. C H 1 1 C5 30. C U 1 4 M47. A U 2 2 D3 31. B U 1 4 N38. A K 1 2 D8 32. A U 2 4 O39. A U 1 2 E2 33. C U 1 4 O3

10. D H 1 2 E2, 5 34. B U 1 4 P211. C U 1 2 E4 35. B U 2 4 P612. A K 1 2 F2 36. D K 1 4 Q213. C U 1 2 F5 37. A U 1 4 R114. C U 2 2 F8 38. A U 1 5 S115. C K 1 3 H5 39. C H 2 5 S416. D K 1 3 G4 40. D U 1 5 S517. A H 2 3 G3 41. A U 1 5 S618. B K 1 3 G7 42. C U 1 5 T419. C U 2 3 H2 43. B U 2 5 U220. A U 1 3 I3 44. A H 1 5 U521. D K 1 4 J9 45. C U 1 5 U922. D K 1 4 J11 46. B K 1 5 U823. B K 1 4 K3, 4 47. D K 1 5 V324. A H 2 4 K5 48. A U 2 5 W4


016chk - 2 - July 30, 2001


Q B C S CO PLO

1. 1 U 4 1 A3

2. 2 U 2 2 D4

3. 3 U 4 2 F7

4. 4 U 4 3 I4

5. 5 U 4 3 I5

6. 6 U 2 4 K6

7. 7 U 5 4 M5

8. 8 U 4 4 P5

9. 9 K 2 4 R1

10. 10 U 3 5 T2, 6

11. 11 K 2 5 S1

12. 12 U 4 5 W2




LEGEND:

Q = Question Number K = Keyed Response C = Cognitive LevelB = Score Box Number S = Score CO = Curriculum OrganizerPLO = Prescribed Learning Outcome

016chk - 3 - July 30, 2001







1. The mass of a burning candle is monitored to determine the rate of combustion of paraffin.An accepted reaction for the combustion of paraffin is:

2 85 56 5828 58 2 2 2C H O CO H Os g g g( ) ( ) ( ) ( )+ → +

The following data is observed:

Time(min)

Mass of Candle(g)

0.0

6.0

12.0

18.0

24.0

30.0

25.6

25.1

24.5

23.9

23.4

22.8

016chk - 4 - July 30, 2001

a) Calculate the average rate of consumption of paraffin in g min for thetime interval 12 0. to 24 0. minutes. (2 marks)

Solution:

For Example:

rmass

tg

g

= ←

= ←

= ←

∆∆

12

12

mark

1 mark

mark

1 112 0

0 092

.. min

. min

b) Calculate the rate of CO2 production in mol min for the timeinterval 12 0. to 24 0. minutes. (2 marks)

Solution:

For Example:

rate gmol C H

gmol CO

mol C H

mol

= × ×

= ×

←−

0 0921

394 056

2

6 5 10

28 58 2

28 58

3

. min.

. min

2 marks

016chk - 5 - July 30, 2001

2. Write four statements that apply to all chemical equilibrium systems. (2 marks)

Solution:

For example any four of the following for 12 mark each:

• system must be closed

• temperature is constant

• forward and reverse rates are equal

• macroscopic properties are constant

• can be achieved from either direction

• concentration of reactants and products are constant

016chk - 6 - July 30, 2001


H Br HBr K2 2 2 14 8g g g eq( ) ( ) ( )+ →← = .

A closed container was initially filled with equal moles of H2 and Br2 .

When equilibrium is reached, the HBr[ ] is 0 329. mol L . What was the initial H2[ ] ?(4 marks)

Solution:

For Example:

H Br HBr

I

C

E

2 2 2

0

0 1645 0 1645 0 329

0 1645 0 1645 0 329

g g g

x x

x x

( ) ( ) ( )+ →←

[ ]

[ ] − − +

[ ] − −

. . .

. . .

KHBr

H Br

M

H mol L

eq

x x

x

= [ ][ ][ ]

= ( )−( ) −( )

=

[ ] =

2

2 2

2

2

14 80 329

0 1645 0 1645

0 250

0 250

..

. .

.

.

← 2 marks

← 2 marks

016chk - 7 - July 30, 2001

4. Calculate the molar solubility of SrF2. (4 marks)

Solution:

For Example:

SrF Sr Fs s

22 2

2

→← ++ −

←1 mark

K Sr F

s s

s mol L

sp = [ ] [ ]= ( )( )

= ×

= ×

+ −

−

−

2 2

2

9

3

2

4 3 10

1 0 10

.

.

← 3 marks


016chk - 8 - July 30, 2001

5. Does a precipitate form when 3 0. mL of 1 0 10 3. × − M NaBr is added

to 2 0 1 0 10 33 2. .mL of M Pb NO× ( )− ? (4 marks)

Solution:

For Example:

PbBr Pb Br22 2s aq aq( ) ( )

+( )

−→← +

PbmLmL

M M

BrmLmL

M M

Trial K Pb Br

2 3 4

3 4

2 2

4 4 2

10

2 05 0

1 0 10 4 0 10

3 05 0

1 0 10 6 0 10

4 0 10 6 0 10

1 4 10

+ − −

− − −

+ −

− −

−

[ ] = × × = ×

[ ] = × × = ×

= [ ] [ ]= ×( ) ×( )= ×

.

.. .

.

.. .

. .

.

sp

Since Trial Ksp is less than Ksp 6 6 10 6. ×( )− no precipitate forms.

← 1 mark

← 2 marks

← 1 mark

016chk - 9 - July 30, 2001

6. Write the equation for the predominant reaction between HSO4− and H PO2 4

− .(2 marks)

Solution:

HSO H PO SO H PO4 2 4 42

3 4− − −+ →← + ← 2 marks

016chk - 10 - July 30, 2001

7. A 0 20. M solution of a weak acid, HA, has a pH = 1 32. .Use calculations and the table of “Relative Strengths of Brønsted-Lowry Acidsand Bases” from the Data Booklet to determine the identity of the acid. (5 marks)

Solution:

For Example:

pH

H O M

=

[ ] =+

1 32

0 0483

.

.

HA H O H O A

I

C

E

+ →← +

[ ]

[ ] − + +

[ ]

+ −2 3

0 20 0 0

0 048 0 048 0 048

0 152 0 048 0 048

.

. . .

. . .

KH O A

HAa = [ ][ ][ ] = ( )( ) = ×

+ −−3 20 048 0 048

0 1521 5 10

. ..

.

The acid is: H SO2 3

← 1 mark

← 2 marks

←1 mark

← 1 mark

016chk - 11 - July 30, 2001

8. Calculate the pH of a solution prepared by mixing 15 0. mL of 0 50. M HClwith 35 0. mL of 1 0. M NaOH. (4 marks)

Solution:

For Example:

moles HCl L M mol= × = × −0 0150 0 50 7 50 10 3. . .

moles NaOH L M mol= × = × −0 0350 1 0 3 5 10 2. . .

excess moles NaOH mol mol mol= × − × = ×− − −3 5 10 7 50 10 2 75 102 3 2. . .

NaOH OHmol

LM

H O

pH

[ ] = [ ] = × =

[ ] = × = ×

=

−−

+−

−

2 75 100 050

0 55

1 0 100 55

1 8 10

13 74

2

3

144

..

.

..

.

.

← 4 marks


016chk - 12 - July 30, 2001

9. Identify a gas which causes acid rain, and write an equation showingthis gas reacting with water. (2 marks)

Solution:

For Example:

One of the following gases: SO SO NO2 3 2, ,

SO H O H SO

SO H O H SO

NO H O HNO HNO

2 2 2 3

3 2 2 4

2 2 3 22

+ →

+ →

+ → +

or

or

← 1 mark

← 1 mark

016chk - 13 - July 30, 2001

10. Balance the following redox reaction in acidic solution. (3 marks)

MnO Fe Mn Fe acidic42 2 3− + + ++ → + ( )

Solution:

For Example:

1 8 5 4

5

8 5 4 5

42

22 3

42 2

23

× + + → +( )× → +( )

+ + → + +

− + − +

+ + −

− + + + +

MnO H e Mn H O

Fe Fe e

MnO H Fe Mn H O Fe

← 3 marks

016chk - 14 - July 30, 2001

11. Aluminum is a stronger reducing agent than copper. What is meant by theterm stronger reducing agent? (2 marks)

Solution:

For Example:

Species that more readily loses electrons. ← 2 marks

016chk - 15 - July 30, 2001

12. Consider the electrolysis of water.

a) Draw and label the parts of an electrolytic cell capable of decomposing water. (3 marks)

Solution:

For Example:

1.0 M H2SO4

DCPowerSource

InertElectrode B

InertElectrode A

1 mark for inert electrodes

1 mark for electrolytic cell

1 mark for suitable electrolyte

b) Identify the gas produced at the anode. (1 mark)

Solution:

O2 ← 1 mark

END OF KEY

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PART A: MULTIPLE CHOICE Value: 60 marks Suggested … · Consider the following potential energy diagram for a ... Which of the following represents the predominant reaction ... select