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JOM CHEMISTRY A1 TOPIC: Salts Name: …………………………………………. Date Received : ………………… Form: …………………… Date Completed: ……………….. Qualitative Analysis of Salts In the qualitative analysis of salts, we need to identify the ions that are present in salts. This can be done by analysing their physical and chemical properties. Observations on the physical properties of salts 1. Colour and solubility in water Certain physical properties of salts such colour and solubitity in water are observed to help us infer certain cations and anions that are present in salts. Table shows the colour of salts in solid , in aqueous solution and the solubility of salts in water Salt Colour in solid Solubility in water Colour in Aqueous solution 1. Ammonium chloride NH 4 Cl 2. Ammonium nitrate NH 4 (NO 3 ) 2 3. Calcium carbonate CaCO 3 4. Calcium nitrate Ca(NO 3 ) 2 5. Magnesium sulphate MgSO 4 1 What is Qualitative analysis? ……………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………...

Exercises Salts

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Page 1: Exercises Salts

JOM CHEMISTRY A1

TOPIC: Salts

Name: …………………………………………. Date Received : …………………

Form: …………………… Date Completed: ………………..

Qualitative Analysis of Salts

In the qualitative analysis of salts, we need to identify the ions that are present in salts. This can be done by analysing their physical and chemical properties.

Observations on the physical properties of salts

1. Colour and solubility in water

Certain physical properties of salts such colour and solubitity in water are observed to help us infer certain cations and anions that are present in salts.

Table shows the colour of salts in solid , in aqueous solution and the solubility of salts in water

Salt Colour in solidSolubility in water

Colour in Aqueous solution

1. Ammonium chloride NH4Cl

2. Ammonium nitrate NH4(NO3)2

3. Calcium carbonate CaCO3

4. Calcium nitrate Ca(NO3)2

5. Magnesium sulphate MgSO4

6. Magnesium carbonate MgCO3

7. Zinc sulphate ZnSO4

8. Zinc nitrate Zn(NO3)2

9. Lead(II) chloride , PbCl2

10. Lead(II) sulphate , PbSO4

11. Lead(II) carbonate , PbCO3

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What is Qualitative analysis?……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………...

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12. Copper(II) chloride , CuCl2

13 Copper(II) sulphate , PbSO4

14. Copper(II) carbonate , PbCO3

15. Iron(II) sulphate , FeSO4

16. Iron(III) chloride , FeCl3

17. Sodium nitrate , NaNO3

18, Sodium carbonate , Na2CO3

19. Potassium nitrate , KNO3

20. Potassium carbonate , K2CO3

Table shows the colour of different cations in solid form and in aqueous solution

Observation Inference

Blue solution

Pale green solution

Yellow/Yellowish-brown/brown solution

Green solid

Brown solid

White solid

Colourless solution

Table shows the solubility of different types of salts in waterCompounds Solubility in water

Sodium saltsPotassium saltsAmmonium salts

Nitrate salts

Chloride salts

Sulphate salts

Carbonate salts

2. Tests for gases

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Gases are often produced from reactions carried out during laboratory tests on salts. By identifying the gases evolved,it is possible to infer the types of cations and anions that are present in a salt.

Table shows the test and the result of different gases

Gas Test Result

Oxygen gas, O2

Hydrogen gas , H2

Carbon dioxide gas , CO2

Ammonia gas, NH3

Chlorine gas, Cl2

Hydrogen chlorine gas , HCl

Sulphur dioxide gas , SO2

Nitrogen dioxide gas , NO2

3. Action of heat on salts

Effect of heat on carbonate saltsCarbonaate salt Colour of salt before

heating Colour of residue Effect on lime water Hot cold

Copper (II) carbonate, CuCO3

Zinc carbonate , ZnCO3

Lead(II) carbonate, PbCO3

Sodium carbonate, Na2CO3

Calcium carbonate, CaCO3

Potassium carbonate, K2CO3

Magnesium carbonate, MgCO3

Effect of heat on nitrate saltsNitrate Salt Colour of salt before

heating Colour of residue Test on gases liberated Hot cold

Copper (II) nitrate, Cu(NO3)2

Zinc nitrate, Zn(NO3)2

Lead(II) nitrate, Pb(NO3)2

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Sodium nitrate, NaNO3

Calcium nitrate, Ca(NO3)2

Potassium nitrate, KNO3

Magnesium nitrate, Mg(NO3)2

Iron(II) nitrate, Fe(NO3)2

Iron(III) nitrate, Fe(NO3)3

The table shows the comparison of the effect of heat on carbonate and nitrate saltsMetal Effect of heat on carbonate salt Effect of heat on nitrate saltPotassiumSodiumCalciumMagnesiumAluminiumZincIronTinLeadCopperMercurySilverGold

Most sulphate salts are not decomposed by heat. Only a few sulphate such as iron(II) sulphate,zinc sulphate and copper sulphate decompose to sulphur dioxide or sulphur trioxide gas when heated.

All chloride salts are stable when heated except ammonium chloride. Ammonium chloride sublimes and decomposes to produce ammonia gas and hydrogen chloride gas.

The table shows the deduction of the types of ion present based on the gas produced

Type of gas produced Type of ion present

CO2

O2

NO2

SO2

NH3

Do it Yourself !

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1. State three examples ofa) soluble salts b) insoluble salts

2. Which of the following salts is soluble

3. Identify the gas that turns moist red litmus paper blue

4. Gas X has the following properties

Gas X is ___________________________________________

5. Heat +

Colour of metal oxide X is yellow when hot and white when cold. Gas Y turns lime water milky.

a) Name gas Y ___________________________________________________b) Name metal oxide X ____________________________________________c) Name salt P __________________________________________________d) Write an equation to represent the action of heat on salt P

6. A sample of copper(II) nitrate, Cu(NO3)2 was heated strongly. Write down the expected observation.

Qualitative Analysis of SaltsTests for anions

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Lead(II) chloride Sodium carbonate

Calcium sulphate Barium sulphate

Colourless Acidic gas Turns lime water milky

Salt P Metal oxide X Gas Y

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Reagent / Condition Observation Anion Ionic Equation (if any)

2 cm3 the unknown solution + dilute hydrochloric acid / nitric acid / sulphuric acid pour into a test tube gas liberated is immediately bubbled through lime water.

2 cm3 of nitric acid + 2 cm3 of the unknown solution pour into a test tube + 2 cm3 silver nitrate solution

2 cm3 of dilute hydrochloric acid / nitric acid + 2 cm3 of the unknown solution pour into a test tube + 2 cm3 of barium chloride / barium nitrate solution shake well

2 cm3 of the unknown solution pour into a test tube 2 cm3 of dilute sulphuric acid + 2 cm3 of iron(II) sulphate solution shake well. Then drop carefully and slowly a few drops of concentrated sulphuric acid along the side of a slanting test tube into the mixture without shaking it.

Confirmatory Test for Fe 2+ , Fe 3+ , Pb 2+ , NH 4+ Ions

Confirmatory Test for Fe 2+ Reagent Observation ConclusionPotassium hexacyanoferrate(II) solution

Pale blue precipitate

Dark blue precipitate

Potassium hexacyanoferrate(III) solution

Dark blue precipitate

Greenish-brown solution

Potassium thiocyanate solution

Pale red colouration

Blood red colouration

Confirmatory Test for Pb2+

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Method Observation Ionic Equation

Using aqueous solution of chloride - 2 cm3 of any solution of Cl- + 2 cm3 of any solution of Pb2+ dilute with 5 cm3 of distilled water heat until no further change occurs allow the content to cool to room temperature using running water from the tap

Using aqueous solution of iodide - 2 cm3 of any solution of I- + 2 cm3 of any solution of Pb2+ dilute with 5 cm3 of distilled water heat until no further change occurs allow the content to cool to room temperature using running water from the tap

When heated –

When cooled –

Confirmatory Test for NH4+

Method Observation

2 cm3 of any solution of NH4+ + 2 cm3 of

NaOH / KOH / Ca(OH)2 heat put a piece of moist red litmus paper at the mouth of the test tube

Reaction with Nessler Reagent 2 cm3 of any solution of NH4

+ + 2 cm3 of Nessler Reagent shake well

Do It Yourself !

Describe chemical tests that can be carried out in the laboratory to differentiate between

(a) lead(II) nitrate solution and aluminium nitrate solution

(b) aluminium nitrate solution and zinc nitrate solution

(c) ammonium chloride solution and potassium chloride solution

(d) iron(II) sulphate solution and iron(III) sulphate solution

(e) sodium chloride and sodium sulphate

REVISION EXERCISE 1

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1. Write the formulae of the following ions.

Ions Formula Ions Formula

Sodium ion Chloride ion

Potassium ion Nitrate ion

Zinc ion Sulphate ion

Magnesium ion Carbonate ion

Calcium ion Hydroxide ion

Lead (II) ion

Copper(II) ion

Ammonium ion

REVISION EXERCISE 2

1. Write the formulae of the following ionic compounds.

Ions Chloride, Cl- Nitrate, NO3- Sulphate, SO4

2- Carbonate, CO32-

Sodium, Na+

Potassium, K+

Zinc, Zn2+

Magnesium, Mg2+

Calcium, Ca2+

Lead (II), Pb2+

Copper(II), Cu2+

Ammonium, NH4+

2. Write the formulae of the following salts.

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Sodium nitrate : ………………………… Potassium sulphate : ………………………

Magnesium chloride : ………………………… Copper(II) sulphate :………………………

Calcium chloride : ………………………… Zinc sulphate :………………………

Lead (II) nitrate : ………………………… Calcium carbonate :………………………

Sodium carbonate : ………………………… Potassium chloride :………………………

3. Write the formulae of the following acids/ bases/ alkalis.

Copper(II) oxide :………………………… Magnesium oxide :………………………...

Lead (II) oxide :………………………… Sodium hydroxide :………………………...

Potassium hydroxide :………………………… Ammonium hydroxide: ……………………….

Hydrochloric acid :………………………… Nitric acid :………………………...

Sulfuric acid :………………………… Ethanoic acid :………………………...

REVISION EXERCISE 3

1. Complete the following.

Acid + Base / alkali ………………... + ...……………….

Acid + Reactive metal …………………+ ………………….

Acid + Carbonate metal …………………+ ………………… + ………….………..

2. Complete the following equations.

a) HCl(aq) + PbO(s) ……………….. + ………………….

b) HNO3(aq) + NaOH(aq) ……………….. + ………………….

c) HCl(aq) + NH4OH(aq) ……………….. + ………………….

d) H2SO4(aq) + CuCO3(s) ……………….. + ……………… + ………………

e) HCl(aq) + Na2CO3(s) ……………..… + ……………… + ………………

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f) HCl(aq) + Mg(s) ……………….. + ………………….

g) H2SO4(aq) + CuO(s) ……………….. + …….……………

h) HNO3(aq) + Zn(s) ……………….. + ………………….

i) HNO3(aq) + MgO(s) ……………….. + ………………….

j) HNO3(aq) + CuCO3(s) …………..…… + ……………… + ……….………

k) H2SO4(aq) + NaOH(aq) ……………….. + ………………….

l) HNO3(aq) + PbCO3(s) ……………….. + ……………… + …….…………

3. Write the chemical equation of each of the following reactions.

a) Dilute hydrochloric acid reacts with magnesium

…………………………………………………………………………………………b) Dilute sulphuric acid reacts with zinc oxide

…………………………………………………………………………………………c) Dilute nitric acid reacts with copper(II) carbonate

…………………………………………………………………………………………d) Dilute sulphuric acid reacts with potassium hydroxide solution

…………………………………………………………………………………………e) Dilute nitric acid reacts with copper(II) oxide

…………………………………………………………………………………………f) Dilute sulphuric acid reacts with lead(II) carbonate

…………………………………………………………………………………………g) Dilute hydrochloric acid reacts with sodium hydroxide solution

…………………………………………………………………………………………h) Dilute sulphuric acid reacts with zinc

…………………………………………………………………………………………i) Dilute sulphuric acid reacts with ammonia aqueous

…………………………………………………………………………………………

REVISION EXERCISE 41 Write the formula of salts formed from each of the following reaction.

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a) Sulphuric acid + copper(II) carbonate

……………………………………………………………………………………………………b) Nitric acid + potassium hydroxide solution

……………………………………………………………………………………………………c) Hydrochloride acid + ammonium hydroxide solution

……………………………………………………………………………………………………

2 Give example s of salts formed from their corresponding acids.Acid Salt Example

Hydrochloric acid Chloride salt

Sulphuric acid Sulphate salt

Nitric acid Nitrate salt

Carbonic acid Carbonate salt

3 Determine whether each of the following salt is soluble or insoluble in water.Salt Solubility ( , X ) Formulae

1. Magnesium chloride2. Lead(II) sulphate3. Calcium carbonate4. Zinc chloride5. Silver chloride6. Potassium carbonate7. Lead(II) nitrate8. Sodium sulphate9. Ammonium chloride10. Barium sulphate11. Copper(II) nitrate12. Copper(II) sulphate13. Copper(II) carbonate14. Iron(II) nitrate15. Iron(III) chloride16. Sodium carbonate17. Ammonium carbonate18. Silver nitrate19. Tin(II) chloride20. Zinc sulphate

4. Write the chemical equation of each of the following reactions.

a) Hydrochloric acid + copper(II) oxide : …………………………………………………

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b) Nitric acid + lead(II) carbonate :………………………………………………….

c) Sulphuric acid + zinc :………………………………………………….

d) Hydrochloric acid + magnesium oxide :………………………………………………….

e) Nitric acid +calcium carbonate :…………………………………………………..

f) Sulphuric acid + magnesium :…………………………………………………..

5. Name a acid and a metal, metal oxide or metal carbonate that can be used to prepare the following salts.

a) Copper(II) sulphate : …………………………………………………………………………

b) Lead(II) nitrate :………………………………………………………………………….

c) Zinc chloride : …………………………………………………………………………

6. Name two aqueous solutions that can be used to prepare the following salts. Write the chemical equation of each reaction.

a) lead(II) sulphate :……….………………………………………………………………….

b) Silver chloride : ………………………………………………………………………….

c) Zinc carbonate : ………………………………………………………………………….

d) Barium sulphate : ………………………………………………………………………….

7. Write the ionic equation of each of the precipitate reactions below.a) Copper(II) nitrate solution + sodium carbonate solution

…………………………………………………………………………………………………b) Zinc chloride solution + lead(II) nitrate solution

…………………………………………………………………………………………………. c) Dilute sulphuric acid + barium nitrate solution

…………………………………………………………………………………………………. d) Silver nitrate solution + hydrochloride acid

………………………………………………………………………………………………….

Mastery Exercise 8.1Name the salt and state whether each of the following salt is soluble or insoluble in water.

No Formula of Salt Name of Salt Solubility ( , X )

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1 PbCO3

2 NaCl3 CaSO4

4 AgNO3

5 K2CO3

6 AlCl3

7 Na2SO4

8 NH4NO3

9 CuSO4

10 PbCl2

11 ZnCO3

12 Ca(NO3)2

13 Na2CO3

14 AgCl15 PbSO4

16 Pb(NO3)2

17 (NH4)2CO3

18 HgCl2

19 Na2SO4

20 NaNO3

21 MgCO3

22 KCl23 (NH4)2SO4

24 Cu(NO3)2

25 SnCO3

26 CaCl2

27 BaSO4

28 KNO3

29 Ag2CO3

30 MgCl2

31 Ag2SO4

32 Ba(NO3)2

33 FeCO3

34 NH4Cl35 Fe(NO3)3

36 MgSO4

37 BaCO3

38 ZnCl2

39 FeSO4

40 Mg(NO3)2

Mastery Exercise 8.2: Describe the preparation of soluble salts (not Na, K, NH4

+ salt)

Soluble salt Copper(II) sulphate, CuSO4

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Name two chemical substances to prepare the salt 1. …………..…………………………..

2. ………………………………………

Chemical equation

Procedure: (Diagram) Description

Mastery Exercise 8.3: Describe the preparation of soluble salts of Na, K and NH4

+

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Soluble salt Sodium Chloride, NaCl

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Name two chemical substances to prepare the salt 1. …………..…………………………..

2. ………………………………………

Chemical equation

Procedure: (Diagram) Description

Mastery Exercise 8.4: Describe the preparation of insoluble salts

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Soluble salt Lead(II) iodide, PbI2

Name two chemical substances to prepare the salt 1. …………..…………………………..

2. ………………………………………

Chemical equation

Ionic equation

Procedure: (Diagram) Description

Numerical Problems involving stoichiometric reactions in the precipitation of salts

Question 1:A student prepare copper(II) nitrate, Cu(NO3)2 by reacting copper(II) oxide, CuO with 200 cm3 of 2.0

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moldm-3 nitric acid, HNO3. Calculate the mass of copper(II) oxide, CuO needed to react completely with the acid. [Relative atomic mass: Cu, 64 ; O, 16]

Question 2:X cm3 of 0.5 moldm-3 sulphuric acid, H2SO4 is added to 100 cm3 of 1.0 moldm-3 lead(II) nitrate solution to produce lead(II) sulphate, PbSO4.

a. Calculate the value of X.b. Calculate the mass of lead(II) sulphate obtained.

[Relative atomic mass: Pb, 20; O, 16; S, 32]

Question 3:Ammonium phosphate, (NH4)3PO4 is used as a fertiliser. 29.8 g of this salt is prepared by neutralising phosphoric acid, H3PO4 with ammonia gas, NH3. Calculate the volume of ammonia gas, NH3 reacted at room conditions.

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[Ar = H, 1; N, 14; P, 31; O, 16. Molar volume: 24 dm3 mol-1 at room conditions]

Question 4:Silver salts such as silver iodide, AgI are used in photography. A sample of the insoluble salt, AgI is prepared by mixing 50 cm3 of 1.0 mol dm-3 silver nitrate, AgNO3 solution and 50 cm3 of 1.0 mol dm-3 potassium iodide, KI solution. Calculate the mass of silver iodide, AgI produced.[Ar = Ag, 108; I, 127]

Question 4:Acids reacts with calcium carbonate, CaCO3 in limestone to form a salt and carbon dioxide, CO2. A piece of limestone reacted completely with 100 cm3 of 31.5 g dm-3 nitric acid, HNO3. [Ar = H, 1; C, 12; N, 14; O, 16; Ca, 40. Molar volume: 24 dm3 mol-1 at room conditions]

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a. Calculate the mass of salt produced. b. What is the volume of carbon dioxide, CO2 liberated at room conditions?

Prepared by;Kamal Ariffin Bin SaaimSMKDBL

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