INSTITUT PERGURUAN TUN HUSSEIN ONN

83000, BATU PAHAT, JOHOR

PRACTICAL SCIENCE 2 – CHEMISTRY 2

QUALITATIVE ANALYSIS

NAME

MOHD NOOR FAIZAL BIN ISMAIL

COURSE

PPISMP SC/BI/BM AMBILAN JULAI 2009

NO I/C

890706-11-5481

LECTURER

ENCIK AHMAD SHUKRI BIN AHMAD@ ABD. HALIM

SUBMIT DATE

05 FEBRUARY 2010

SEMESTER 2 Practical Science 2 (Experiment 5)

Topic : Qualitative analysis

Purpose : To determine the cations and anions of inorganic substances

Theory : Chemical analysis is the process by which we can find out the composition of a substance by breaking it down into its constituents. Qualitative analysis is used to find the elements present in a given compound or mixture. Reactions of the cations and anions with specific reagents enable its identity to be obtained.

Materials : Dilute hydrochloric acid, distilled water, aqueous sodium hydroxide, aqueous ammonia, aqueous ammonium chloride, aqueous iron(III) chloride, aqueous silver nitrate, dilute niric acid, aqueous disodium hydrogen phosphate and potassium chromate(VI) and lime water.

Apparatus : Boiling test, test tube, litmus paper, bunsen burner, wooden splinter, filter paper, conical flask, and filter funnel

Control variable : Room temperature

Manipulative variable : Lime water, litmus paper, wooden splinter

Response variable : Colour changes precipitate formed, cloudy lime water.

Procedure :

1. Dilute hydrochloric acid is added to small amount of solid KA 1, and then that

sample is warmed gently. Then, litmus paper is used to detect if that solution

is acid or alkali. Lime water also used to detect the present of carbon dioxide.

2. Solids KA 1 and KA 2 are simple salts. To identify the cations and anion of

KA 1, the following experiments are carry out.

3. The solid KA 1 is dissolved in distilled water in conical flask. Then, the mixture

of distilled water and KA 1 is filtrate by using filter paper into another conical

flask.

4. The product of filltration is separate into six part, which is put it into six

different test tube for tests.

5. An aqueous sodium hydroxide is added into first test tube and after that, add

in excess.

6. For the second test tube, an aqueous ammonia is added and the followed by

aqueous ammonium chloride in excess.

7. For the third test tube, an aqueous iron(III) chloride is added and then warm

gently. Then, litmus paper is used to detect if that solution is acid or alkali

8. After that, an aqueous silver nitrate is added into forth test tube and then

followed by dilute nitric acid.

9. An aqueous disodium hydrogen phosphate is added into the fifth test tube

10.For the last test tube, aqueous potassium chromate(VI) is added and followed

by dilute hydrochloric acid.

11.All the observation and deduction are recorded in the table below

12.The steps from 1 to 11 is repeated for KA 2

Results :

Tests of KA 1

Test Observation Deduction(c) add dilute hydrochloric acid to a small amount of solid KA 1, then warm gently

Solid of KA 1 dissolved in diluted hydrochloric acid and more soluble in warm condition

Meaning that, the solid of KA 1 is a salt in organic form

(d) dissolve solid KA 1 in distilled water and filter. Use separate portions of the filtrate for test (i) to (vi)

i. Add aqueous sodium hydroxide, then in excess

White precipitate formed and insoluble in excess

Magnesium(II) ion, Mg2+, and calcium(II) ion, Ca2+

ii. Add aqueous ammonia, then in excess followed by aqueous ammonium chloride

White precipitate formed and insoluble in excess but soluble in ammonium chloride

Magnesium(II) ion, Mg2+, aluminium(III) ion, Al3+, plumbum(II) ion, Pb2+

iii. Add aqueous iron(III) chloride, then warm

Litmus paper change from blue to red

The moist chlorine gas will show the acidity properties

iv. Add aqueous silver nitrate, followed by dilute nitric acid

Black precipitate Ag+ + SO32- Ag2 SO3

v. Add aqueous disodium hydrogen phosphate

White precipitate Mg2+ + HPO42- MgHPO4

vi. Add aqueous potassium chromate(VI) followed by dilute hydrochloric acid

Green precipitate and yellow precipitate

2CrO42- + 2H+ Cr2O7

2- + H2O (orange)

CrO42- (yellow)

Reduction : Cr2O72- Cr3+

Oxidation : O2 2O2- + 4e-

Identity of KA 1: Magnesium(II) ion salts (MgSO3)

Tests of KA 2

Test Observation Deduction(c) add dilute hydrochloric acid to a small amount of solid KA 1, then warm gently

Solid of KA 2 dissolved in diluted hydrochloric acid and more soluble in warm condition. Lime water turn to milky

Meaning that, the solid of KA 2 is a salt in organic form

CuCO3 + HCl CuCl2 + CO2 + H2O

(d) dissolve solid KA 1 in distilled water and filter. Use separate portions of the filtrate for test (i) to (vi)

i. Add aqueous sodium hydroxide, then in excess

Blue precipitate and insoluble in excess

Copper(II) ion, Cu2+

ii. Add aqueous ammonia, then in excess followed by aqueous ammonium chloride

Blue precipitate and dissolve in excess

Copper(II) ion, Cu2+

iii. Add aqueous iron(III) chloride, then warm

Yellow precipitate formed and changed to reddish

Cu2+ + Cl- CuCl2 (yellow)

iv. Add aqueous silver nitrate, followed by dilute nitric acid

White precipitate If react : Ag+ + CO32- Ag2CO3

Also react : 2AgNO3 + CuCl2 2AgCl + Cu(NO3)2

v. Add aqueous disodium hydrogen phosphate

Light blue solution formed

Cu2+ + HPO42- CuHPO4

(blue complex)vi. Add aqueous potassium chromate(VI) followed by dilute hydrochloric acid

Yellow precipitate formed

Cr2O72- + H2O CrO4

2-

Identity of KA 2: Copper (II) ions, Copper Carbonate (CuCO3)

Discussion :

1. The potassium chromate (VI) K2CrO4 given was replaced by potassium

dichromate (VI) K2Cr2O7

2. The lime water prepared in this experiment was very saturated so that it was very

sensitive to detect the carbon dioxide, CO2 and turns milky

3. The same dropper which being used in this experiment were used several times

with the same chemical substances.

4. The changes of SO32- to S was the reduction process because of the decreasing

of the oxidation number.

SO32- S

X(+1) + 3(-2) = -2 X = 0

X = 4

4. The chemical substances used had been oxidized by the oxygen.

5. Carbon dioxide, CO2 in air diffuse with the lime water and made it turn milky faster

6. The observations of the chemical substances were not effective ang gave the

inaccurate results of the experiments.

Conclusion :

KA 1 is a magnesium(II) ion salts (MgSO3) and KA 2 is a Copper(II) ions in (CuCO3)