Chemical Analysis Assignment (IP) Ans

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Chemistry (IP)

Qualitative Analysis Assignment

Name: Date:

Class: Mark: / 75

Identify and write the chemical name and formula for the unknown in the following reaction schemes. Write a balanced chemical equation for the reactions.

chemical name and formula chemical name and formula

P Copper(II) carbonate, CuCO3 U Copper(II) sulfate, CuSO4

Q Copper(II) chloride, CuCl2 V Barium sulfate, BaSO4

R Copper(II) hydroxide, Cu(OH)2 W Carbon dioxide, CO2

S Copper(II) oxide, CuO X Calcium carbonate, CaCO3

T Sulfuric acid, H2SO4

Equations:

P Q: CuCO3 (s) + 2HCl (aq) CuCl2 (aq) + CO2 (g) + H2O (l)

Q R: CuCl2 (aq) + 2NaOH (aq) Cu(OH)2 (s) + 2NaCl (aq)

R S: Cu(OH)2 (s) CuO (s) + H2O (g)

S U: CuO (s) + H2SO4 (aq) CuSO4 (aq) + H2O (l)

U V: CuSO4 (aq) + Ba(NO3)2 (aq) BaSO4 (s) + Cu(NO3)2 (aq) [14]

green

solid P

dilute hydrochloric acid

green

solution Q +

colourless

gas W

sodium hydroxide

solution

calcium hydroxide

solution

blue

precipitate R

white

precipitate X

heat black

precipitate S

dilute

acid T

solution U

aqueous barium nitrate white

precipitate V

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A Zinc, Zn D Zinc hydroxide, Zn(OH)2

B Zinc chloride, ZnCl2 E Water vapour, H2O

C Hydrogen, H2 F Zinc oxide, ZnO

Equations:

A B: Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g)

D F: Zn(OH)2 (s) ZnO (s) + H2O (g)

C E: 2H2 (g) + O2 (g) 2H2O (g) Questions: Predict the colour of solid F when it cools down. White

Describe what will be observed if dilute hydrochloric acid is added dropwise into solution G until no further observation.

White precipitate will form and will dissolve in excess hydrochloric acid to form a colourless solution.

Describe a chemical test for E.

It will turn blue cobalt(II) chloride paper pink / It will turn white anhydrous copper(II) sulfate powder blue.

[14]

grey

solid A

dilute hydrochloric acid colourless

solution B +

colourless

gas C

burn in air

colourless

gas E

aqueous ammonia

white

precipitate D

excess aqueous

ammonia

hot yellow

solid F

colourless

solution G

heat

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M Iron(III) chloride, FeCl3 R Iron, Fe

N Silver chloride, AgCl S Iron(III) nitrate, Fe(NO3)3

O Iron(III) hydroxide, Fe(OH)3 T Iron(II) sulfate, FeSO4

P Iron(III) sulfate, Fe2(SO4)3 U Hydrogen, H2

Q Iron(III) oxide, Fe2O3

Equations:

M N: FeCl3 (aq) + 3AgNO3 (aq) 3AgCl (s) + Fe(NO3)3 (aq)

M O: FeCl3 (aq) + 3NaOH (aq) Fe(OH)3 (s) + 3NaCl (aq)

O Q: 2Fe(OH)3 (s) Fe2O3 (s) + 3H2O (g)

O P: 2Fe(OH)3 (s) + 3H2SO4 (aq) Fe2(SO4)3 (aq) + 6H2O (l)

R S: 2Fe (s) + 6HNO3 (aq) 2Fe(NO3)3 (aq) + 3H2 (g)

R T: Fe (s) + H2SO4 (aq) FeSO4 (aq) + H2 (g) Question: Describe what will be observed if aqueous ammonia is added dropwise into

solution T until no further observations?

Dirty green precipitate is formed which is insoluble in excess aqueous ammonia

[17]

brown

solution M

sodium hydroxide solution brown

precipitate O

silver nitrate solution

white precipitate N

heat strongly

brown solid Q

heat strongly with carbon

grey metallic

solid R *

dilute sulfuric acid

green solution T + colourless

gas U

dilute sulfuric acid brown

solution P

dilute nitric acid orange

solution S

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P Calcium, Ca T Ammonia, NH3

Q Calcium hydroxide, Ca(OH)2 U Calcium sulfate, CaSO4

R Hydrogen, H2 V Carbon dioxide, CO2

S Calcium carbonate, CaCO3 W Calcium oxide, CaO

Equations:

P Q: Ca (s) + 2H2O (l) Ca(OH)2 (aq) + H2 (g)

R T: 3H2 (g) + N2 (g) 2NH3 (g)

Q S: Ca(OH)2 (aq) + CO2 (g) CaCO3 (s) + H2O (l)

S U: CaCO3 (s) + H2SO4 (aq) CaSO4 (s) + H2O (l) + CO2 (g)

P W: 2Ca (s) + O2 (g) 2CaO (s) Question: Describe what will be observed if aqueous sodium hydroxide is added

dropwise into solution Q until no further observations?

White precipitate is formed which is insoluble in excess sodium hydroxide

[15]

grey metallic

solid P

water colourless

solution Q +

colourless

gas R

carbon dioxide

white

precipitate S

dilute sulfuric acid

+ colourless

gas V

white

precipitate U

nitrogen, catalyst, high temperature & pressure

colourless

gas T

oxygen in air

white solid

W

Universal Indicator

blue solution

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A Lead(II) nitrate, Pb(NO3)2 E Ammonia, NH3

B Lead(II) iodide, PbI2 F Copper(II) nitrate, Cu(NO3)2

C Lead(II) hydroxide, Pb(OH)2 G Copper(II) hydroxide, Cu(OH)2

D Lead(II) sulfate, PbSO4

Equations:

A B: Pb(NO3)2 (aq) + 2KI (aq) PbI2 (s) + 2KNO3 (aq)

A C: Pb(NO3)2 (aq) + 2NaOH (aq) Pb(OH)2 (s) + 2NaNO3 (aq)

A D: Pb(NO3)2 (aq) + H2SO4 (aq) PbSO4 (s) + 2HNO3 (aq)

E G: 2NH3 (g) + 2H2O (l) + Cu(NO3)2 (aq) Cu(OH)2 (s) + 2NH4NO3 (aq) Questions: Describe what will be observed if gas E is continuously bubbled into solution

containing blue precipitate G?

Blue precipitate dissolves to form a dark blue solution

Explain why the above reaction scheme cannot be that of iron compounds?

Iron compounds are usually coloured, i.e. green for iron(II) compounds and brown for iron(III) compounds. None of these colours are present in the above reaction scheme.

[14]

colourless

solution A

aqueous sodium hydroxide

white

precipitate C

dilute sulfuric acid white

precipitate D

aqueous potassium

iodide yellow

precipitate B

blue

precipitate G

aqueous F nitrate colourless

gas E

litmus solution

blue solution

excess aqueous ammonia white

precipitate colourless solution

excess aqueous sodium hydroxide

aluminium powder, warm

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Question: Black solid S reacts with dilute acid T to form a green solution U. When

aqueous ammonia is added to a portion of U, a dirty green precipitate V is formed. A creamy yellow precipitate W is formed when aqueous silver nitrate is added to a portion of U. Write the chemical name of S, T, U, V and W.

S: iron(II) nitrate, Pb(NO3)2 T: hydroiodic acid U: iron(II) iodide V: iron(II) hydroxide W: silver iodide [5]

Question: Metal A burns in yellow-green gas B to form a white solid C which dissolves

into water to form a colourless solution. When aqueous sodium salt D is added into aqueous C, a white precipitate E which does not react with dilute nitric acid is formed. When aqueous carbonate F is added into aqueous C, a white precipitate G is formed. When alkaline solution of carbonate F is warmed, it produces a gas H which turned moist red litmus paper blue. A: calcium, Ca B: chlorine gas, Cl2 C: calcium chloride, CaCl2 D: sodium sulfate, Na2SO4 E: calcium sulfate, CaSO4 F: ammonium carbonate, (NH4)2CO3 G: calcium carbonate, CaCO3 H: ammonia gas, NH3 [8] Describe how you test for pale green gas B in the laboratory. Gas B will turn moist blue litmus red, then bleached.

[2]

End of Assignment

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Chemical Analysis Assignment (IP) Ans