8 salts 2010

WAJA F4 Chemistry 2010 CHAPTER 8: SALT

CHAPTER 8 : SALTS

A. SYNTHESISING SALTS

Learning Outcomes You should be able to: state examples of salts used in daily life, explain the meaning of salt identify soluble and insoluble salts, describe the preparation of soluble salts, describe the purification of soluble salts by recrystallisation, list physical characteristics of crystals, describe the preparation of insoluble salts, write chemical and ionic equations for reactions used in the preparation

of salts, design an activity to prepare a specified salt, construct ionic equations through the continuous variation method solve problems involving calculation of quantities of reactants or products in stoichiometric reactions

Activity 1 : Meaning and uses of Salts

1. A salt is an ……………………..……… formed when the ……………….. ion, from an ……………

is replaced by a ……………. ion or an …………………..ion.

2. Example of salts : Complete the table below

Acid Formula of acid

Salt Formula Cation Anion

Sodium chloride NaCl Na+ Cl-

Potassium carbonate K2CO3

Copper(II) sulphate CuSO4

Ammonium nitrate NH4NO3

Magnesium nitrate Mg(NO3)2

Sodium ethanoate CH3COONa

3. Match the following salts with their uses.

Salts Uses

Barium sulphate BaSO4 Fungicide Calsium sulphate CaSO4 Bleaching agent Iron sulphate FeSO4 Paint for yellow line on roadAmmonium nitrate NH4NO3 X-ray ‘meals’ in hospital Copper(II) sulphate CuSO4 Nitrogenous fertilizerSodium chloride NaCl Toothpaste Sodium hydrogen carbonate Iron tablets, for anaemia

patient

Sodium nitrite NaNO2 Baking powderSodium hypochlorite NaOCl

Preserve food

Tin(II) fluoride SnF2 A flavouring Lead(II) chromate PbCrO4 Plaster of Paris for broken

bone

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Activity 2 : Identify soluble and insoluble salt.

Fill in the blanks with the correct word(s)

1. All ………………. , ………………., and …………………. salts are soluble in water.

2. All ………………. salts are soluble in water.

3. All sulphate salts are soluble in water except …………….. sulphate, …………. sulphate and ………… sulphate.

4. All chloride salts are soluble in water except …………….. chloride , …………. chloride and ………… chloride.

5. All carbonate salts are insoluble in water except …………….. carbonate, …………. carbonate and ………… carbonate

6. State whether each of the following salt is soluble or insoluble in water

No Formula of Salt Solubility ( , X ) No Formula of Salt Solubility ( , X )1 PbCO3 21 MgCO3

2 NaCl 22 KCl3 CaSO4 23 (NH4)2SO4

4 AgNO3 24 Cu(NO3)2

5 K2CO3 25 SnCO3

6 FeCl3 26 CaCl27 Na2SO4 27 BaSO4

8 NH4NO3 28 KNO3

9 CuSO4 29 Ag2CO3

10 PbCl2 30 MgCl211 ZnCO3 31 ZnSO4

12 Ca(NO3)2 32 Ba(NO3)2

13 Na2CO3 33 FeCO3

14 AgCl 34 NH4Cl15 PbSO4 35 Fe(NO3)3

16 Pb(NO3)2 36 MgSO4

17 (NH4)2CO3 37 BaCO3

18 HgCl2 38 ZnCl219 Na2SO4 39 FeSO4

20 NaNO3 40 Mg(NO3)2

2

Water

Na+

K+

NH4+

Ba2+

Ca2+

Pb2+Pb2+

Ag+

Hg2+NO3

-

Water

SO4 2-

Cl- CO3 2-

Na+

K+

NH4+

NO3 -Ba2+

Ca2+

Pb2+

Pb2+

Ag+

Hg+


Activity 3 : Write chemical and ionic equations for reactions used in the preparation of soluble salts

1. Complete these general equation for preparing soluble salts.

a. metal + acid …………… + …………………….

b. metal oxide (or metal hydroxide) + acid …………… + ……………………

c. alkali + acid …………… + …………………….

d. metal carbonate + acid …………… + ……………… + ……………………….

2. Using the general equations in question 1, complete the following chemical equation. It may also be necessary to balance the equation.

a. Mg + H2SO4 …………… + …………………….

b. (i) CuO + HCl …………… + ……………………

(ii) Zn(OH)2 + HNO3 ................................... + .........................

c. NaOH + HCl ………………….. + ……………………….

d. MgCO3 + H2SO4 …………… + ……………… + ……………………….

3. Deduce the identity of the acid, metal, salt, or other product by filling in the missing details in this table of preparation of soluble salt

Method of Preparation

Reactants Salt Formed Other Product

a) metal + acid Magnesium + ……………… Magnesium chloride Hydrogen

b) metal oxide + acid Copper(II) oxide + sulphuric acid

……………………… …………….

c) metal carbonate + acid

……………… + ……………… Zinc sulphate Water + …………….

……………..

d) metal hydroxide + acid

……………… + ……………… Potassium nitrate ……………

f) alkali + acid ……………… + ……………… Sodium chloride ……………

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4. Name the reactants which are needed to prepare the following soluble salts:

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

(b) Zinc chloride : …………………………………………………………………………….

(c) Potassium nitrate : ……………………………………………………………………………..

(d) Ammonium sulphate : ……………………………………………………………………………..

(e) Magnesium nitrate : ……………………………………………………………………………..

5. Rewrite each of the following chemical equation as ionic equation. Shown below is an example where a chemical equation can be simplified into an ionic equation.

Example : Chemical equation : Zn(s) + H2SO4(aq) ZnSO4(aq) + H2(g) Zn + 2H+ + SO4

2- Zn2+ + SO42- + H2

(s) (aq) (aq) (aq) (aq) (g)

Ionic equation : Zn(s) + 2H+ (aq) Zn2+ (aq) + H2(g)

a. Chemical equation : Mg(s) + 2HCl(aq) MgCl2(aq) + H2O

Ionic equation : .........................................................................................................................

b. Chemical equation : MgO(s) + 2HCl(aq) MgCl2(aq) + H2O

Ionic equation : ........................................................................................................................

c. Chemical equation : NaOH (aq) + HNO3 (aq) NaNO3 (aq) + H2O (l)

Ionic equation : .......................................................................................................................

d. Chemical equation : CuCO3 (s) + H2SO4 (aq) CuSO4 (aq) + CO2 (g) + H2O (l)

Ionic equation : .......................................................................................................................

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Activity 4 : Write out the procedure for the preparation of soluble salts of sodium, potassium and ammonium

Soluble salt Sodium Chloride, NaCl

Name two chemical substances to prepare the salt

1. …………..…………………………..

2. ………………………………………

Chemical equation

Procedure: (Diagram) Description

Describe the physical characteristics of the crystals that you obtained

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Activity 5 : Write out the procedure for the preparation of soluble salts (not sodium, potassium or ammonium salt)Soluble salt Copper(II) sulphate, CuSO4


1. …………..…………………………..

2. ………………………………………Chemical equation


Describe the purification process of the crystals

6


Activity 6 : Write chemical and ionic equations for reactions used in the preparation of insoluble salts

1. Insoluble salts can be prepared by ………………….. method through ……………………………..

reaction. In this reaction, two different aqueous solution mutually exchange their …….. to form

………………………….

Soluble salt solution + Soluble salt solution Insoluble salt MX containing cation M+ containing anion X-

Chemical equation : AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3(aq)

Ionic equation : Ag+ (aq) + Cl- (aq) AgCl (s)

2. Preparation of insoluble salts Example 1: Barium sulphate,

Solution 1: ……………………………………... Solution 2: ……….………………………………….

Chemical equation : ………………………………………………………………..……………………..

Ionic Equation : …………………………………………………………………………………………….

Observation : White precipitate formed

Example 2: Copper(II) carbonate, CuCO3

Solution 1: …………………………………….. Solution 2: ……………………………………….

Chemical equation : …………………………………………………………………………………….

Ionic Equation : ………………………………………………………………………………………….

Observation : ……………….. precipitate formed

Example 3: Lead(II) chromate(VI),

Solution 1: …………………………………….. Solution 2: …………………………………….

Chemical equation : ………………………………………………………………………………….

Ionic Equation : ………………………………………………………………………………………..

Observation : ……………….. precipitate formed

Activity 7 : Describe the preparation of insoluble salts

7


Insoluble salt Lead(II) iodide, PbI2


1. …………..…………………………..

2. ………………………………………

Chemical equation

Ionic equation


8


Activity 8 : Construct ionic equation for the formation of lead(II) chromate through the continuous variation method,

Figure 1

Figure 1 shows seven test tubes for the reaction between lead(II) nitrate Pb(NO3)2 0.5 mol dm-3 and potassium chromate(VI) K2CrO4 0.5 mol dm-3.

(a) Calculate the number of moles of lead(II) nitrate Pb(NO3)2 and potassium chromate(VI) K2CrO4

used in test tubes 1-7. Using a ruler, measure the height of lead(II) chromate(VI) precipitate formed. Record all these in Table 1as well as complete Table 1.

Test Tube 1 2 3 4 5 6 7

Volume of Pb(NO3)2 /cm3 5.0 5.0 5.0 5.0 5.0 5.0 5.0

No of mole of Pb(NO3)2

Volume of K2CrO4 /cm3 1.0 2.0 3.0 4.0 5.0 6.0 7.0

No of mole of K2CrO4

Height of precipitate / cm

Colour of solution above precipitate

Table 1

9

Test tube 2… 2.cm3 of potassium chromate (VI), test tube 3…3 cm3 varying the volumes of potassium chromate (VI)…

Fixed the volumes of lead (II) nitrate at 5.0 cm3.

1 2 3 4 5 6 7


(b) Based on Table 1, draw a graph of the height of the precipitate against volume of lead (II) nitrate solution on the graph paper.

(c) On the graph that you have drawn in (b), (i) mark and write the minimum volume of potassium chromate(VI) solution needed for complete

reaction with 5.0 cm3 of lead(II) nitrate solution 0.5 mol dm-3.

(ii) Calculate the number of moles of chromate(VI) ions that has reacted with 1 mole of Pb2+. ions.

(iii) Write the formula of lead(II) chromate.

………………………………………………………………………………………………………………(iv) Write the ionic equation for the formation of lead(II) chromate(VI).

………………………………………………………………………………………………………………(d) What can you observed about the height of the precipitate in Figure 1?

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

……………………………………………………………………………………………………………..(e) What is your inference based on your answer in (d)?

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

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

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

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Activity 9 : Solve problems involving calculation of quantities of reactants or products in stoichiometric reactions

Example 1 : A student prepares copper (II) nitrate by reacting copper (II) oxide with 100 cm3

1.5 mol dm-3 nitric acid. Calculate the mass of copper (II) oxide need to react completely with the acid. [Relative atomic mass: Cu, 64 ; O, 16]

Solution : Chemical equation : CuO + 2HNO3 Cu(NO3)2 + H2O

Mole ratio : 1 mole 2 mole 1 mole 1 mole Number of moles of HNO3 = 1.5 x 100 = 0.15 mol 1000 Mole ratio of CuO : HNO3 = 1 : 2

Number of mole of CuO = 1 x 0.15 = 0.075 mole 2 Mass of CuO = 0.075 x (64 + 16) = 6 g

Question : 1 Excess zinc powder is added to react completely with 50 of 2.0 hydrochloric acid.(a) Write an ionic equation for the reaction between zinc and hydrochloric acid.

(b) Calculate the number of moles of hydrochloric acid used.

(c) Calculate the volume of hydrogen gas liberated at room conditions.[Molar volume: 24 ]

2 Excess of magnesium carbonate powder, MgCO3, is reacted with 100 cm3 of a 1 mol dm-3

sulphuric acid H2SO4 , What is the mass of magnesium sulphate formed?[Relative atomic mass : Mg =24, O=16, S = 32 ]

3. 0.12 g of magnesium reacts with excess hydrochloric acid to produce hydrogen gas. Given that

the relative molecular mass of H=1, Mg = 24, CI =35.5 and 1 mol of gas occupies 24 dm3 at room temperature and pressure. Fnd the (a) mass of salt formed (b) volume of gas produced

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Example 2 : A sample of insoluble lead (II) sulphate is prepared by mixing 50 cm3 of 1.0 mol dm-3

lead (II) nitrate solution and y of 1.5 mol dm-3 sulphuric acid. [Relative atomic mass: O, 16 ; S, 32 ; Pb, 207]

(a) Calculate the volume, y, of the sulphuric acid needed to react completely with the lead (II) nitrate solution.

Solution :Chemical equation : Pb(NO3)2 + H2SO PbSO4 + 2 HNO3

Mole ratio : 1 mole 1 mole 1 mole 2 mole Number of moles of Pb(NO3)2 = 1.0 x 50 = 0.05 mol 1000

Mole ratio of Pb(NO3)2 : H2SO4 = 1 : 1

Number of mole of H2SO4 reacted = 0.05 mol 1.5 x y = 0.05 mole

1000 y = 0.05 x 1000 = 33.33 cm3

1.5 (b) Calculate the mass of lead (II) sulphate obtained.

Solution :Number of mole of PbSO4 = Number of moles of Pb(NO3)2 = 0.05 molMass of PbSO4 = 0.05 x (207 + 32 + 4 x 16) g

= 15.15 g

Question

4. A sample of insoluble silver chloride is prepared by mixing 50 of 1.0 mol dm-3 silver nitrate solution and z of 0.5 sodium chloride solution. [Relative atomic mass: Ag 108; Cl 35.5]

(a) Write the chemical equation for the reaction between silver nitrate and sodium chloride.

(b) Calculate the volume, z, of the sodium chloride needed to react completely with the silvernitrate solution.

(c) Calculate the mass of silver chloride obtained.

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B. SYNTHESISING QUALITATIVE ANALYSIS OF SALTS

Learning Outcomes You should be able to: state examples of salts used in daily life, explain the meaning of salt identify soluble and insoluble salts, describe the preparation of soluble salts, describe the purification of soluble salts by recrystallisation, list physical characteristics of crystals, describe the preparation of insoluble salts, write chemical and ionic equations for reactions used in the preparation

of salts, design an activity to prepare a specified salt, construct ionic equations through the continuous variation method solve problems involving calculation of quantities of reactants or products in stoichiometric reactions

Activity 10 : Qualitative Analysis

1. Qualtitative analysis of a salt is a chemical technique used to identify the …….. that are present

in a salt by analysing its ………………. and ……………………. properties.

2. Make inferences on the following substances based on their colour: (use formula of substance when writing your answer. Make it is correct!)

Colour (solid or solution) Substance or cation or anionGreen powder Salt: CationBlue powder Cation: Brown powder Cation:Black powder Two metal oxides: Yellow powder when hot and white when coldBrown powder when hot and yellow when coldBlue solution Cation:Pale green solution Cation:Brown solution Cation:Solid : WhiteSolution : colourless

6 cations :

Solid : WhiteSolution : colourless

4 anions :

3. Complete the following table

Salts Solubility in water ColourInsoluble white

Copper(II) carbonateIron(II) sulphate

Soluble BrownLead(II) sulphateMagnesium carbonateZinc chlorideAmmonium carbonate

Insoluble Yellow

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Activity 11 : Confirmatory Tests for gases,

Complete the observation for the confirmatory test for gases

Gas Method Diagram ObservationCarbon dioxide

Bubble the gas produced into lime water

HeatingCarbonate

salts

Oxygen Insert a glowing splinter into the test tube

Nitrogen dioxide

Observe the colour of gas produced. Bring a piece of moist blue litmus paper to the mouth of the test tube

Chlorine Observe the colour of the gas.Bring a piece of moist blue litmus

paper to the mouth of the test tube

Ammonia Dip a glass rod into concentrated hydrochloric acid and bring a drop of acid to the mouth of the test tube/place moist red litmus paper at the mouth of the test tube

.

HydrogenBring a lighted splinter to the mouth of the test tube.

Mg + HCl release hydrogen gas

Hydrogen chloride

Dip a glass rod into concentrated ammonia solution and bring a drop of ammonia to the mouth of test tube

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Tests For Gases


Activity 12 : Action of Heat On Carbonate Salts

Carbonate salts (except Na+ & K+ ) decompose on heating giving off carbon dioxide gas and residue metal oxide

Activity : Complete the chemical equation and observation for the action of heat on carbonate salt

Carbonate salt Action of heatPotassium carbonate K2CO3 , Sodium carbonate Na2CO3

Not decompose by heat

Metal Carbonate metal oxide + carbon dioxideCalcium carbonate

CaCO3 CaO + CO2

Observation : White solid formed. Gas liberated turn lime water chalky

Magnesium carbonateMgCO3 ……….. .. + …. ………

Observation : ……………………………………………….

……………………………………………………………….Aluminium carbonate

Al2(CO3)3 ……….. .. + …. ………

Observation : ……………………………………………….

……………………………………………………………….Zinc carbonate

ZnCO3 ……….. .. + …. ………

Observation : ……………………………………………….

……………………………………………………………….Lead(II) carbonate

PbCO3 ……….. .. + …. ………

Observation : ……………………………………………….

……………………………………………………………….Copper(II) carbonate

CuCO3 ……….. .. + …. ………

Observation : ……………………………………………….

……………………………………………………………….

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Metal oxideColourCopper (II) oxideBlackZinc oxideHot: yellow ;

Cold: WhiteLead (II) oxideHot: brown ; Cold: YellowIron(III)

oxideBrown

Lime water turn chalky


Activity 13 : Action of Heat On Nitrate SaltsNitrates Salts - Decompose on heating liberate nitrogen dioxide gas and oxygen gas except NaNO3 and KNO3 which liberate oxygen gas only

Activity: Complete the chemical equation and observation for the action of heat on nitrate saltNitrate salts Action by Heat

Metal Nitrate metal nitrite + oxygenPotassium nitrate

2KNO3 2 KNO2 + O2

Observation : white solid formed, gas released relighted glowing splinter

Sodium nitrate2NaNO3 ……….. .. + …. ………

Observation : ……………………………………………………….. ……………………………………………………………………….

Metal Nitrate metal oxide + nitrogen dioxide + oxygenCalcium nitrate

2Ca(NO3)2 2CaO + 4NO2 + O2

Observation : white solid formed, Brown gas which turns moist blue litmus red released. Another gas released relighted glowing splinter

Magnesium nitrateMg(NO3)2 ……….. .. + …. ……… + ……………

Observation : ……………………………………………………….. ……………………………………………………………………….

Zinc nitrateZn(NO3)2 ……….. .. + …. ……… + ……………

Observation : ……………………………………………………….. ……………………………………………………………………….

Lead(II) nitratePb(NO3)2 ……….. .. + …. ……… + ……………

Observation : ……………………………………………………….. ……………………………………………………………………….

Copper(II) nitrateCu(NO3)2 ……….. .. + …. ……… + ……………

Observation : ……………………………………………………….. ……………………………………………………………………….

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Brown gas turn moist blue litmus to red(NO2)

Colourless gas relighted glowing splinter (O2 )Heat Heat


Activity 14 : Confirmatory Tests for Anions,

1. Write the ionic equation for the following reactions.

2. Which anion produce the following observations?

a) b)

c) d)

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Inference :

Salt K1

Add BaCl2

solution + HCl acid

Add AgNO3

solution + HNO3 acid

Inference : Effervescence,Gas bubbles,Gas turn lime water chalky

Brown ring formedterhasil

Add FeSO4 solution+ concentrated sulphuric acid

Add sulphuric acid

Inference :

White precipitate

White precipitateformed

Salt K2

Inference :

Salt K3Salt K4

Anions

CO3 2-

Cl-

SO4 2-

NO3 -

+ HNO3

+ AgNO3

+ Dilute acid

+ HCl+ BaCl2

+ H2SO4

+ FeSO4

+ concentrated H2SO4

Effervescence – CO2

Lime water turns milkyIonic equation : …………………………

White precipitate

Ionic equation : …………………………

White precipitate

Ionic equation : …………………………

Brown ring


Activity 15: Reaction of Cations with alkali solution 1. Positive ions are identified by their reactions with a. sodium hydroxide NaOH solution b. Ammonia solution NH3 2. In these reactions, the cations (positive metal ions) produce different coloured precipitate which

may or may not be soluble in excess alkali

Look for precipitate

State whether each of the following precipitate is soluble or insoluble in excess alkali.

NaOH solution Ammonia Solution NH3

A little In excess A little In excess

Soluble ( , X ) Soluble ( , X )Ca2+ White precipitate No changeZn2+ White precipitate White precipitateAl 3+ White precipitate White precipitatePb 2+ White precipitate White precipitateMg2+ White precipitate White precipitateCu 2+ Blue precipitate Blue precipitateFe 2+ Green precipitate Green precipitateFe 3+ Brown precipitate Brown precipitate

Which anion produces the following observations?

a)

b)

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See if Precipitatedissolves

5 drops of alkali(NaOH or NH3)

Solution of cations

Salt K5

Add excess NaOH solution

White precipitateformed

Inference 2 :

Salt K6

Add 5 drops of NH3 solutionAdd NH3 solution in excess

White precipitateDissolves in excess NaOH solution alkali

White precipitatedoes not dissolve in excess NaOH solution

Inference 3:

Inference5 :White precipitateDissolve in excess NH3

White precipitatedoes not dissolve in

White precipitateformed Inference 6:

No white precipitate formed , when heatedAlkali gas released (ammonia) released

Inference 1

No White precipitateformed

Inference 4

Add 5 drops of NaOH solution

Q1

Q2


Activity 16 : Confirmatory Tests for Fe 2+ , Fe 3+ , Pb 2+ and NH 4+

(A) The table shows how confirmatory tests are conducted for ammonium ion, NH4+ , Iron(II) ion,

Fe2+ , Iron(III) ion, Fe3+ , and lead(II) ion, Pb2+ . Complete the confirmatory tests and observation.

Cation Name of Reagent Observation

Add a few drops of ……………………to the test tube containing 2 cm3 of lead(II) nitrate solution ( ions)Add 2 cm3 of distilled water and boil the mixture. Cool the contents using running water from the tap.

……………… precipitate is formed

which ………………..in the hot water

and is ……………… on cooling

Add a few drops of ……………………to the test tube containing 2 cm3 of iron(II) sulphate solution ( ions)

……………….. precipitate is formed

Add a few drops of ……………………to the test tube containing 2 cm3 of iron(III) sulphate solution ( ions)

……………….. solution is formed

4NH

Add a few drops of ……………………to the test tube containing 2 cm3 of

ammonium chloride solution ( 4NH

ions)

……………….. precipitate is formed

The diagram below shows the flow chart for the chemical test of Fe2+ ions and Fe3+ ions.

Based on the flow chart, explain how to differentiate Fe2+ ions and Fe3+ ions.

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

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

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

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

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Solution contains Fe2+ ions or Fe3+ ions.

Light blue precipitate

Dark blue precipitate

Fe2+ ions

Fe3+ ions

K4Fe(CN)6

Potassium hexacyanoferrate(II)

Test II

Solution contains Fe2+ ions or Fe3+ ions.

No change

Blood red solution

Fe2+ ions

Fe3+ ions

Potassium thiocyanate

KSCN

Test I


Activity 17 : Q ualitative analysis to identify salts

(A). Identify the salt S1The following tests were carried out to identify salt S1. Based on the observations given for each test, state its inference. Finally, identify salt S1

Test Observation Inference1. Heat S1 strongly in a test tube. Identify any gas liberated.

Brown gas and gas relight a glowing splinter liberated.Residue is brown when hot and yellow when cold

2. Dissolve a spatulaful of S1 in distilled water. Divide into four portions and

carry out the following tests:

Residue dissolve in acid to produce colourless solution

(a) add solution until excess.

White precipitate, dissolve in excess NaOH solution

(b) add solution until excess

White precipitate, insoluble in excess ammonia solution

(c) add potassium iodide solution

Yellow precipitate formed

(d) add dilute ,

followed by solution. Carefully add about 1 of oncentrated

Brown ring formed

(A). Conclusion for salt S1 : …………………………………………………………………….

(B). Identify the salt S2The following tests were carried out on an aqueous solution of salt S2. Based on the observations given for each test, state its inference. Finally, identify salt S2.

Test Observation Inference1. Pour about 2 of S2 into a test tube. Add solution until excess

White precipitate, dissolve in excess NaOH solution

2. Pour about 2 of S2 into a test tube. Add solution until excess

White precipitate, dissolve in excess ammonia solution

3. Pour about 2 of S2 into a test

tube. Add dilute , followed by

silver nitrate, solution

No change

4. Pour about 2 of S2 into a test tube. Add dilute HCl solution, then add BaCl2 solution

White precipitate

(B). Conclusion for salt S2 : ……………………………………………………………………..

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Activity 18 : plan qualitative analysis to identify anions

Rajoo works in a laboratory. He noticed that there are two large bottles. However both the labels have fallen off. He found four labels beside the bottles. i.e ‘Sodium Chloride Solution’, ‘Sodium Carbonate Solution’, ‘Sodium Sulphate Solution’ and ‘Sodium Nitrate Solution’. So he has to carry out confirmatory test to identify the anion in both the solutions.

Complete the graphic organizers describing four tests and their results. The charts can then be used by Rajoo to distinguish which bottle contains which solution.

CHART A: SODIUM CARBONATE AND SODIUM NITRATE

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Test 1Add dilute HNO3

(or any dilute acid)

Test 2Add dilute H2SO4

followed by ………… solution.Carefully add 1 cm3 of …………………… H2SO4

Test 3Add dilute HNO3, followed by …………… …………., solution

Test 4Add dilute HCl, followed by

……………

……………. solution

SO

DIU

M C

AR

BO

NA

TE

SO

DIU

M N

ITR

AT

E

Result 1

Result 2

Result 3

Result 4

Result 1

Result 2

Result 3

Result 4


CHART B: SODIUM CHLORIDE AND SODIUM SULPHATE

22

Test 1Add dilute HNO3

(or any dilute acid)

Test 2Add dilute H2SO4

followed by ………… solution.Carefully add 1 cm3 of …………………… H2SO4

Test 3Add dilute HNO3, followed by …………… …………., solution

Test 4Add dilute HCl, followed by

……………

……………. solution

SO

DIU

M C

HL

OR

IDE

SO

DIU

M S

UL

PH

AT

E

Result 1

Result 2

Result 3

Result 4

Result 1

Result 2

Result 3

Result 4

8 salts 2010

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