Chapter 11 Qualitative Analysis

Question 1

When added aqueous sodium hydroxide and aqueous ammonia , white precipitate, Zn(OH)2 formed. Precipitate dissolves in excess to give a colorless solution, what is the cation?

Answer 1

zinc

Question 2

When added aqueous sodium hydroxide, white precipitate, Al(OH)3 formed. Precipitate dissolves in excess to give a colourless solution.

When added aqueous ammonia, white precipitate, Al(OH)3 formed. Precipitate insoluble in excess, what is the cation?

Answer 2

aluminum

Question 3

When added aqueous sodium hydroxide, white precipitate, Pb(OH)2 formed. Precipitate dissolves in excess to give a colourless solution.

When added aqueous ammonia, white precipitate, Pb(OH)2 formed. Precipitate insoluble in excess, what is the cation?

Answer 3

Lead(II)

Question 4

When added aqueous sodium hydroxide, white precipitate, Ca(OH)2 formed. Precipitate insoluble in excess.

No precipitate formed is form with aqueous ammonia. What is the cation?

Answer 4

Calcium

Question 5

When added aqueous sodium hydroxide, light blue precipitate, Cu(OH)2 formed. Precipitate insoluble in excess.

When added aqueous ammonia, light blue precipitate, (CuOH)2 formed. Precipitate dissolves in excess to give dark blue solution. What is the cation?

Answer 5

Copper(II)

Question 6

When added aqueous sodium hydroxide and aqueous ammonia, green precipitate, Fe(OH)2 formed. Precipitate insoluble in excess. What is the cation?

Answer 6

Iron(II)

Question 7

When added aqueous sodium hydroxide and aqueous ammonia, reddish brown precipitate, Fe(OH)3 formed. Precipitate insoluble in excess. What is the cation?

Answer 7

Iron(III)

Question 8

When added aqueous sodium hydroxide, no precipitate is formed. When heated, ammonia gas is produced and moist red litmus paper turns blue.

No reaction occur when added aqueous ammonia.

Question 8

When added aqueous sodium hydroxide, no precipitate is formed. When heated, ammonia gas is produced and moist red litmus paper turns blue.

No reaction occur when added aqueous ammonia. What is the cation?

Answer 8

Ammonium

Question 9

Add dilute acid. Bubble the gas into limewater, Ca(OH)2, what cation is that?

Answer 9

Carbonate, CO3 2-

Question 10

What is the positive results for carbonate?

Answer 10

Acid will react with CO3 2- ions to produce carbon dioxide. Effervescence observed. White precipitate (CaCO3) will form in limewater. Gas produce is carbon dioxide

Question 11

Add dilute nitric acid, then add silver nitrate solution. What cation is that?

Answer 11

Chloride, Cl-

Question 12

What is the positive results of Chloride, Cl-

Answer 12

White precipitate of silver chloride (AgCl) formed.

Question 13

Add dilute nitric acid, then add barium nitrate solution. What is the cation is that?

Answer 13

Sulfate, SO4 2-

Question 14

What is the positive test for sulfate

Answer 14

White precipitate of barium sulfate (BaSO4) formed.

Question 15

Add dilute sodium hydroxide, then add a piece of aluminum foil. Warm the mixture. Test the gas given off with a piece of moist red litmus paper. What is the cation is that?

Answer 15

Nitrate, NO3-

Question 16

What is the positive test for nitrate

Answer 16

Moist red litmus paper turns blue. Gas produced is ammonia gas.

Question 17

How to test for sulfur dioxide and what is the positive test?

Answer 17

Place a piece of filter paper soaked with acidified potassium manganate(VII) at the mouth of the test tube.

Purple acidified potassium manganate (VII) turns colourless.