TEST FOR ANIONS

Question 1

test for Carbonate CO3 2-

Answer 1

Add dilute H2SO4 and bubble gas produced through limewater.
(Any other suitable dilute acid can be used.)

2H+ (aq) + CO3 2-(aq) –> CO2 (g) + H2O (l)

Question 2

observations for Carbonate CO3 2-

Answer 2

Bubbles of CO2 gas are produced which gives a white precipitate of CaCO3 in limewater.

Question 3

Test for Sulfate SO4 2-

Answer 3

Add dilute HNO3, followed by adding Ba(NO3)2 solution.

Ba2+ (aq) + SO42-(aq) –> BaSO4(s)

Question 4

observations for Sulfate SO4 2-

Answer 4

A white precipitate of BaSO4

is formed.

Question 5

test for chloride Cl-

Answer 5

–> Add dilute HNO3, followed by adding AgNO3 solution.

Ag+ (aq) + Cl-(aq) –> AgCl (s)
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ALTERNATIVE TEST:
–> Add dilute HNO3, followed by adding Pb(NO3)2solution.

Pb2+ (aq) + 2Cl-(aq) –> PbCl2 (s)

Question 6

observation of chloride Cl-

Answer 6

A white precipitate of AgCl is formed.

For the alternative test:
A white precipitate of PbCl2
is formed.

Question 7

test for Iodide

Answer 7

Add dilute HNO3, followed by adding Pb(NO3)2 solution.

Pb2+ (aq) + 2I-(aq) –> PbI2(s)

Alternative test: Add dilute HNO3, then add AgNO3 solution.

Ag2+ (aq) + I-(aq) –>AgI (s)

Question 8

Observation for Iodide

Answer 8

A yellow precipitate of PbI2is formed.

For the alternative test:
A yellow precipitate of AgI is formed.

Question 9

test for Nitrate

Answer 9

Add dilute NaOH, followed by adding a little aluminum powder.
Warm the mixture.

Aluminum reduces NO3- to NH4+ ions:
NH4+(aq) + OH-(aq) –> NH3 (aq) + H2O (l)

Question 10

Observation for Nitrate

Answer 10

Pungent NH3 gas is produced which turns moist red litmus blue.