Salts (Review q)

8/8/2019 Salts (Review q)

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CHAPTER 8 (SALTS)

PAPER 2 ESSAY SECTION A

3 The diagram shows series of reactions for the preparation of copper(II) chloride from copper(II)carbonate.

Based on the diagram,(a) (i) name the solid X

[ 1 mark]

(ii) suggest how to change copper(II) carbonate to solid X in step I.

[ 1 mark]

(iii) explain how gas Y is identified.

...........................................................................................................................................................................[ 2 marks ]

(iv) Draw a labelled diagram of the apparatus that you can use to produce solid X and identify gas Yin step I.

[ 2 marks]

1

Copper(II) carbonate Solid X Colourless gas Y

Solution R

Copper(II) chloride

Step I

Step IIExcess solid X is added to dilute hydrochloricacid

Step III

+


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(b) (i) Why is excess of solid X added to the heated dilute hydrochloric acid in step II?

[ 1 mark]

(ii)Write the chemical equation for the reaction in step II.

[ 1 mark]

(c) Describe how copper(II) chloride crystals are obtained from solution R in step III.

[ 3 marks ]

4 The diagram shows the formation of lead(II) nitrate and its changes to other compounds.

(a) (i) Lead(II) oxide has reacted with compound J to form lead(II) nitrate. Name compound J

...........................................................................................................................................[1 mark]

(ii) Write the chemical equation for the reaction in (a) (i)

...........................................................................................................................................

[1 mark]

(b) (i) Name the brown gas.

...........................................................................................................................................[1 mark]

(ii) Write the chemical equation for the reaction in (b) (i)

..........................................................................................................................................

[1 mark](c) When copper(II) chloride solution is added to lead(II) nitrate solution, a precipitate Z and

copper(II) nitrate are produced.

(i) Name the type of reaction occurs.

...........................................................................................................................................[1 mark]

2

Lead(II) oxide Lead(II) nitrate+ compound J Brown gas

+ copper(II) chloride solution

Compound Z copper(II) nitrate


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(ii) Write the ionic equation for the formation of compound Z.

...........................................................................................................................................[1 mark]

(iii) State how compound Z is separated from copper(II) nitrate.

...........................................................................................................................................[1 mark]

(d) Sodium hydroxide solution is added a little at a time to lead(II) nitrate solution until in excess.What is the observation?

........................................................................................................................................................[2 marks]

PAPER 2 ESSAY SECTION B SECTION C

11 (a) Name a soluble salt and an insoluble salt.

Write a chemical equation for the preparation of each type of salt given by you.[4 marks]

(b) You are given zinc nitrate crystals. Describe how you can perform a chemical test to confirm thepresence of zinc ions and nitrate ions in the zinc nitrate crystals.

[6 marks]

(c) You are required to prepare magnesium nitrate salt from the chemical substances provided below.

Your answer should include all the chemical equations involved in the reactions.[10 marks]

3

Magnesium sulphate solution

Dilute nitric acid

Sodium carbonat solution


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Sample answer Chapter 8

3(a) (i) Copper(II) oxide 1(ii) Heat strongly 1(iii) Passed the gas through the lime water , the lime water turns chalky 1

1 + 1

(b)(i) All hydrochloric acid has reacted 1

(ii) CuO + 2HCl CuCl2 + CO2 + H2O 1+1(c) Heat the solution until saturated, cool the solution , filter and dry with filter paper 1

Total 9

4(a) (i) nitric acid (dilute) 1(ii) PbO + HNO3 Pb(NO3)2 + H2O 1

(b) (i) Nitrogen dioxide 1(ii) 2Pb(NO3)2 2PbO + 4NO2 + O2 1

(c) (i) Precipitation reaction 1

(ii) Pb2+ + 2Cl- PbCl2 1

(ii) Filter, rinse with distill water1

(d) White precipitate 1

Dissolve in excess of sodium hydroxide solution 1

11(a) [Able to name a soluble salt and insoluble salt]

Example:

1 Soluble salt: copper(II) sulphate 1

2 Insoluble salt: barium sulphate 1

3 H2SO4 + CuO CuSO4 + H2O //H2SO4 + CuCO3 CuSO4 + H2O + CO2 1

4 BaCl2 + Na2SO4 BaSO4 + 2NaCl 1

[Notes] :- All nitrate salts are soluble.

- All potassium, sodium and ammonium salts are soluble.

- All sulphate salts are soluble except PbSO4, CaSO4 and BaSO4.

4

Lime water

Copper(II) carbonate

Heat


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- All chloride salts are soluble except PbCl2, AgCl and HgCl2.- All carbonate salts are insoluble except K2CO3, Na2CO3 and (NH4)2CO3

(b) [Able to give appropriate chemical test]

1 Zinc nitrate crystals are dissolved in distilled water and 1the solution is divided into two portions in two test tubes. 1

2 For the first portion, ammonia solution is added drop by drop untill in excess. 13 A white precipitate is formed and insoluble in excess ammonia solution. 14 For the second portion, dilute sulphuric acid is added follow by iron(II) sulphate solution.

The mixture is shaken well. 15 Then, concentrated sulphuric acid is added carefully down the side of the test tube. 16 A brown ring is formed.

(c) [Able to describe the procedure to prepare magnesium nitrate salt ]

1 Magnesium sulphate solution is added to sodium carbonate solution in a beaker. 1

2 The mixture is shaken well/ stirred and a white solid, MgCO3 is formed. 13 The white precipitate is filtered out and rinsed with distilled water. 1

4 The white precipitate is added to the nitric acid in a beaker until in excess/ some of it nolonger dissolves. 1

5 The excess white precipitate is filter out. 16 The filtrate is poured into an evaporating dish. 1

7 The salt solution is gently heated until saturated. 18 The hot saturated salt solution is allowed to cool for crystals to form. 1

9 The crystals formed are filtered out, washed with a little cold distilled water. 1and dried between sheets of filter paper.

Max8

10 Chemical equations:

MgSO4 + Na2CO3 MgCO3 + Na2SO4 1

MgCO3 + 2HNO3 Mg(NO3)2 + H2O + CO2 1

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Salts (Review q)