2019 Senior External Examination: Chemistry Paper One — Question and response … · 2020-05-11 · 4 2019 hemistry — uestion and response book — Paper One Section 2 — Short

Candidate usePrint your candidate number here

Attach barcode here

Number of books used

Supervisor use only

Supervisor’s initials

QCAA use only

Marker number

1 9 – –

2019 Senior External Examination

ChemistryPaper One — Question and response book

Friday 25 October 20199 am to 11:40 am

Time allowed• Perusal time: 10 minutes

• Working time: 2 hours 30 minutes

Examination materials provided• Paper One — Question and response book

• Paper One — Resource book

• Paper One — Multiple-choice response sheet

Equipment allowed• QCAA-approved equipment

• non-programmable calculator

DirectionsDo not write during perusal time.

Paper One has two parts:• Part A — Knowledge of subject matter

Section 1 — Multiple choice (attempt all questions) Section 2 — Short response (attempt all questions)

• Part B — Scientific processes (attempt four questions only)

Suggested time allocation• Part A: 1 hour 50 minutes

• Part B: 40 minutes

AssessmentPaper One assesses the following assessment criteria:

• Knowledge of the subject matter

• Scientific processes

Assessment standards are at the end of this book.

After the examination sessionThe supervisor will collect this book when you leave.

Planning space

12019 Chemistry — Question and response book — Paper One

Part A assesses knowledge of subject matter and its simple application based on the eight topics in the Chemistry Senior External Syllabus 1998 (amended 2006).Part A is worth 70 marks.Suggested time allocation: 1 hour 50 minutes.

Section 1 — Multiple choiceSection 1 has 10 questions worth 1 mark each. Attempt all questions.Each question contains four options. Select the option that you think is correct or is the best option. Respond on the multiple-choice response sheet.

Question 1Which of the following have approximately that same mass?

A A neutron and a proton

B A proton and an electron

C An electron and a neutron

D An electron and a hydrogen atom

Question 2An element whose atoms are held together by only dispersion forces would be located in which group of the periodic table?

A 2B 10C 17D 18

Question 3Bromoethene, C2H3Br, reacts with oxygen as shown in the equation below:

2 3 2 2 22C H Br 5O 4CO 2H O 2HBr+ → + +

How many moles of CO2 are produced when 3.0 moles of C2H3Br and 3.0 moles of O2 are reacted together?

A 2.4

B 3.0

C 3.8

D 6.0

Part A — Knowledge of subject matter

2 2019 Chemistry — Question and response book — Paper One

Question 4

In which of the following compounds does chromium have an oxidation number of +2?

A CrO3

B CrCl2C K2CrO4

D KCr(SO4)2

Question 5The unbalanced equation for the conversion of methanol to methanoic acid is shown below.

24 3MnO CH OH HCOOH Mn− ++ → +___ ___ ___ ___

The balanced equation would also include

A H+ and H2O on the left.

B H+ and H2O on the right.

C H+ on the left and H2O on the right.

D H+ on the right and H2O on the left.

Question 6The structure below represents which type of biological molecule?

A Fats

B Esters

C Proteins

D Carbohydrates


Question 7A section of the periodic table has had the chemical symbols replaced by letters.

Which element is located in the d-block of the periodic table?A J

B G

C E

D A

Question 8The partial pressure of a gas depends on

A the shape of the molecule.

B the shape of the container.

C the molecular mass of the particle.

D the number of molecules of gas in the vessel.

Question 9In an exothermic reaction, the

A products have higher enthalpy than the reactants.

B reactants release heat and therefore have higher enthalpy.

C heat of reaction is positive as the products have higher energy.

D reactants absorb heat and therefore the reaction container would feel cold.

Question 10Which species represent a conjugate acid–base pair in the equation below?

3 2 3 3CH COOH(aq) H O(l) CH COO (aq) H O (aq)− ++ +

A H3O + / H2O

B H2O / CH3COO –

C CH3COO – / H3O +

D CH3COOH / H2O

End of Section 1


Section 2 — Short responseSection 2 has eight questions worth 60 marks in total. Attempt all questions.Write your responses in the spaces provided. Show all working.If you need more space for a response, continue at the back of this book. Label any continued response with the question number.

Question 11 — Materials: Properties, bonding and structurea. Name the substance that is represented by the formula MgCl2.

(1 mark)

b. Chlorine can exist as two naturally occurring isotopes 3517 Cl

and 37

17 Cl.

Deduce how the particle components of the two nuclei of chlorine are:

i. the same.

ii. different.

(2 marks)

c. Draw the Lewis structure for BCl3 and predict its shape.

Molecule Lewis structure Shape

BCI3

(3 marks)

d. Describe two characteristics of the intermolecular bonds in BCl3.

(2 marks)


Question 12 — Reacting quantities and chemical analysisa. Explain the following terms:

i. molar mass

(1 mark)

ii. molarity

(1 mark)

b. Calcium carbonate (CaCO3) reacts with phosphoric acid (H3PO4) to produce a precipitate (Ca3(PO4)2) and carbon dioxide (CO2).

i. Rewrite the chemical equation for this reaction as a balanced equation.

3 3 4 3 4 2 2 2CaCO (s) H PO (aq) Ca (PO ) (s) H O(1) CO (g)+ → + +

(2 marks)

ii. Calculate the number of moles of H3PO4(aq) in 200.0 mL of 0.10 M solution.

(1 mark)

iii. Calculate the theoretical mass of Ca3(PO4)2(s) precipitate formed when 200.0 mL of 0.10 M H3PO4(aq) is reacted with 1.50 g of CaCO3(s).

(4 marks)


Question 13 — Oxidation and reductiona. Explain the term oxidising agent (oxidant) in terms of transfer of electrons.

(1 mark)

b. Determine the oxidation number of Cr in the dichromate ion, 22 7Cr O −.

(1 mark)

c. Draw a labelled diagram of a galvanic cell with one half-cell consisting of nickel and a solution of 1.0 M nickel ions and the other half-cell consisting of zinc and a solution of 1.0 M zinc ions.

i. On your diagram label the:• anode and cathode• direction the electrons flow• movement of the ions.

(3 marks)

ii. Calculate the voltage produced by the cell above.

(1 mark)


Question 14 — Organic chemistrya. Apply IUPAC rules to name the following:

(2 marks)

b. Explain the term geometric isomerism.

(2 marks)

c. Arrange the following organic compounds in order from lowest to highest boiling point. Justify your answer.

propanal propane propanol

i. Order:

(1 mark)

ii. Justification:

(3 marks)


Question 15 — Chemical periodicitya. For each of the following electron configurations, identify the element and state the period or group

that it belongs to in the periodic table.

Species Electron configuration Element Period Group

A neutral atom 1s2 ............. 4p3 4

An ion with one negative charge 1s2 ............. 3p6 17

(2 marks)

b. The first six ionisation energies (IE) of the nitrogen atom, are shown below (kJ mol–1).

IE1 IE2 IE3 IE4 IE5 IE6

1 400 2 580 4 560 7 450 9 460 53 100

Explain three reasons why IE6 is much greater than IE5.

(3 marks)


Question 16 — Gases and the atmospherea. Describe the relationship between temperature and solubility of a gas in a liquid.

(1 mark)

b. Use the kinetic theory of gases to explain the relationship between pressure and the number of moles of gas (when volume and temperature are constant).

(3 marks)

c. Describe the conditions under which real gases approach ideal gas behaviour.

(1 mark)


Question 17 — Energy and rates of chemical reactionsa. Define the term activation energy.

(1 mark)

b. Use collision theory to explain how the temperature of the system influences the rate of reaction.

(3 marks)

c. Marble is composed of calcium carbonate (CaCO3) which reacts with hydrochloric acid (HCl) as shown in the balanced equation below:

3 2 2 2CaCO (s) 2HCl(aq) CaCl (aq) CO (g) H O(1)+ → + +

On the axes below, sketch a labelled diagram for the rate of reaction curves for the following two reactions, if temperature is held constant.

• Reaction A: 1 gram of crushed marble is reacted with 100 mL of 1.0 M HCl.

• Reaction B: 1 gram of marble chips is reacted with 100 mL of 1.0 M HCl .

Time (s)

Volu

me

of C

O2 (

mL)

(3 marks)


Question 18 — Chemical equilibriuma. Describe the term strong electrolyte.

(2 marks)

b. The formation of nitrogen(II) oxide, NO, is shown by the equation:1

2 2N (g) O (g) 2NO(g) 181 kJ mol−+ ∆ ° =H

i. State the equilibrium law expression, Kc , for the above equation.

(1 mark)

ii. 1.6 mol of N2(g) and O2(g) are placed into an empty 1.0 L container. At equilibrium the concentration of NO(g) is 0.66 mol dm–3. Calculate the value of the equilibrium constant, Kc , for this mixture.

(3 marks)

iii. Explain the effect that a decrease in temperature would have on the Kc for this reaction.

(3 marks)

Question 18 continues over next page ▬►


c. Calculate the pH of a solution that results from dissolving 1.0 g of sodium hydroxide (NaOH) in1.0 L of pure water.

(3 marks)

End of Section 2End of Part A


Part B — Scientific processes

Part B assesses scientific processes based on the eight topics in the Chemistry Senior External Syllabus 1998 (amended 2006) and practical work undertaken during your study of the subject.Part B has five questions of equal value. Attempt four questions only. If you respond to all five questions, only your first four responses will be assessed.Suggested time allocation: 40 minutes.

Question 1 — Oxidation and reductionA student set up an experiment using strips of four different metals (J, L, M and Q) which were placed into four different solutions that contained J2+, L2+, M2+ and Q2+ ions respectively. The following results were obtained:

J2+ L2+ M2+ Q2+

J Not tested x x x

L x Not tested x x

M Not tested x

Q Not tested

x = no reaction = reacted

a. Use the information in the table to arrange the metals in order of reactivity with the most reactive metal first. Justify how you arrived at your response.

i. Order:

ii. Justification:

b. Explain which two metals (J, L, M, Q) would produce the greatest potential difference in an electrochemical cell. (Include appropriate half-equations.)

c. A new metal, X, is more reactive than metal Q and forms compounds in which it has an oxidation number of +3. Write the balanced equation for the reaction between metal X and the oxide of metal Q.


Question 2 — Materials: Properties, bonding and structureQualitative analysis is a method used to identify ions in solution. The separation of ions is achieved by taking advantage of their solubility properties in water. Once separated, the identity of the ion in the precipitate can be verified by confirmatory tests where the precipitate is dissolved (Table 1) and the resulting solution reacted with a reagent to produce a unique response (Table 2).

Table 1: Confirmatory tests for anion precipitates

Reagent Carbonates (CO3

2–)Chlorides

(Cl–)Hydroxides

(OH–)Phosphates

(PO43–)

Sulfates (SO4

2–)Sulfides

(S2–)conc.

HNO3(aq) s x x s s s

NH3(aq) (excess) x s s x x x

s = soluble x = insoluble

Table 2: Confirmatory tests for cations (precipitates)

Reactants Ag+ Pb2+ Cu2+

HCl(aq) white white green

H2SO4(aq) white white blue

Kl(aq) yellow yellow white

K2CrO4(aq) brown yellow brown

a. i. Use the solubility rules to determine the precipitate formed when aqueous barium nitrate (Ba(NO3)2) is mixed with a solution of sodium sulfate (Na2(SO4)).

ii. Use Table 1 to write a balanced ionic equation to show how the precipitate formed in question 2 a. i. above could be dissolved.


b. Use the solubility rules to complete the qualitative scheme below to show how a nitrate solution containing a mixture of silver, lead and copper ions can be separated into Ag+, Pb2+ and Cu2+ ions one at a time, to form three different precipitates.

c. Describe confirmatory tests that could be used to verify the presence of the Ag+ ion in the silver precipitate.


Question 3 — Reacting quantities and chemical analysisThe table below shows the data obtained when different volumes of a 0.5 M sodium iodide (NaI) solution were reacted with different volumes of a 0.5 M iron nitrate (Fe(NO3)x) solution. The iron iodide produced was collected, dried and weighed.

Trial number

Volume NaI(mL)

Volume Fe(NO3)x(mL)

Mass of iron iodide produced (g)

1 10.0 0.0 0.00

2 9.0 1.0 0.16

3 8.0 2.0 0.31

4 7.0 3.0 0.46

5 6.0 4.0 0.47

6 5.0 5.0 0.39

7 4.0 6.0 0.31

8 3.0 7.0 0.23

9 2.0 8.0 0.15

10 1.0 9.0 0.07

11 0.0 10.0 0.0

a. Draw a graph to show the relationship between the mass of the FeIx precipitate formed and volume of Fe(NO3)x solution used. Spare graphs are on pages 24 and 25 at the end of this book.


b. Explain the shape of the graph by considering the chemical reaction that has occurred.

c. Interpret the graph to:

i. identify the volume ratio that will produce the maximum mass of iron iodide.

ii. determine the formula of the iron iodide produced.


Question 4 — Gases and the atmospherea. Describe an experimental procedure to determine the number of moles of gas produced by collecting

the gas generated when magnesium carbonate (MgCO3) reacts with hydrochloric acid (HCl) to produce carbon dioxide (CO2) gas.

Experimental procedure

Labelled sketch of experimental set-up


b. Justify your chosen procedure.

c. Explain two possible sources of experimental error that could arise from the experimental procedure used to collect the gas.


Question 5 — Energy and rates of chemical reactionsAqueous potassium hydroxide (KOH) solution reacts with hydrochloric acid (HCl), as follows, to produce an enthalpy change.

2KOH(aq) HCl(aq) KCl(aq) H O(1)+ → +

To determine the enthalpy change of this reaction, 50.0 mL of 0.500 M KOH solution was mixed rapidly in a glass beaker with 50.0 mL of 0.500 M HCl solution and the change in temperature recorded.

Initial temperature of each solution = 19.6 °C

Final temperature of the mixture = 23.1 °C

a. Determine if the reaction is exothermic or endothermic. Justify your response.

b. Explain why it was important that the solutions were mixed rapidly.

c. Calculate the enthalpy change of this reaction in kJ mol−1. Assume that the specific heat capacity of the solution is the same as water.

d. Identify one possible source of experimental error and explain how it could be reduced.

End of Part BEnd of Paper One


Additional response page






Spare graphs


Spare graphs


Asse

ssm

ent s

tand

ards

from

the C

hem

istry

Sen

ior E

xter

nal S

yllab

us 19

98 (a

men

ded 2006

)Pa

per O

ne

Crite

rion

Very

hig

h ac

hiev

emen

tHi

gh ac

hiev

emen

tSo

und

achi

evem

ent

Limite

d ac

hiev

emen

tVe

ry li

mite

d ac

hiev

emen

t

Know

ledg

e of

subj

ect m

atte

rA

very

high

abili

ty to

reca

ll and

ap

ply k

nowl

edge

of ch

emist

ry in

sim

ple s

ituat

ions

.

A hi

gh ab

ility

to re

call a

nd ap

ply

know

ledg

e of c

hem

istry

in

simpl

e situ

atio

ns.

A sa

tisfa

ctor

y abi

lity t

o rec

all

and

appl

y kno

wled

ge of

ch

emist

ry in

sim

ple s

ituat

ions

.

Limite

d ab

ility

to re

call a

nd

appl

y kno

wled

ge of

chem

istry

in

simpl

e situ

atio

ns.

Very

limite

d ab

ility

to re

call a

nd

appl

y kno

wled

ge of

chem

istry

in

simpl

e situ

atio

ns.

Scie

ntifi

c pro

cess

esA

very

high

abili

ty to

succ

eed

in

simpl

e scie

ntifi

c pro

cess

task

s —

colle

ctin

g and

orga

nisin

g da

ta, p

roce

ssin

g inf

orm

atio

n,

mak

ing s

impl

e jud

gmen

ts,

com

mun

icatin

g inf

orm

atio

n in

va

rious

cont

exts

, dev

ising

and

desig

ning

sim

ple a

nd/o

r sin

gle-

step

inve

stiga

tions

.

A hi

gh ab

ility

to su

ccee

d in

sim

ple s

cient

ific p

roce

ss ta

sks

— co

llect

ing a

nd or

gani

sing

data

, pro

cess

ing i

nfor

mat

ion,

m

akin

g sim

ple j

udgm

ents

, co

mm

unica

ting i

nfor

mat

ion

in

vario

us co

ntex

ts, d

evisi

ng an

d de

signi

ng si

mpl

e and

/or s

ingle

-st

ep in

vest

igatio

ns.

A sa

tisfa

ctor

y abi

lity t

o su

ccee

d in

sim

ple s

cient

ific

proc

ess t

asks

— co

llect

ing a

nd

orga

nisin

g dat

a, p

roce

ssin

g in

form

atio

n, m

akin

g sim

ple

judg

men

ts, c

omm

unica

ting

info

rmat

ion

in va

rious

cont

exts

, de

visin

g and

des

ignin

g sim

ple a

nd/o

r sin

gle-s

tep

inve

stiga

tions

.

Limite

d ab

ility

to su

ccee

d in

sim

ple s

cient

ific p

roce

ss ta

sks.

Very

limite

d ab

ility t

o suc

ceed

in

simpl

e scie

ntifi

c pro

cess

task

s.

© The State of Queensland (Queensland Curriculum and Assessment Authority) 2019

Copyright enquiries should be made to:

ManagerPublishing UnitEmail: publishing@[email protected]

Queensland Curriculum& Assessment AuthorityPO Box 307, Spring Hill QLD 4004 AustraliaLevel 7, 154 Melbourne Street, South BrisbaneT +61 7 3864 0299

www.qcaa.qld.edu.au

Documents

2019 Senior External Examination: Chemistry Paper One — Question and response … · 2020-05-11 · 4 2019 hemistry — uestion and response book — Paper One Section 2 — Short