required practical 4

Question 1

how do you test for sulphate ions?

Answer 1

add acidified aqueous barium chloride solution (acidify with hydrochloric acid)
a white precipitate will form
Ba^2+ (aq) + SO4^2- (aq) -> BaSO4 (s)

Question 2

how do you test for hydroxide ions?

Answer 2

use litmus paper/UI paper
red litmus paper will turn blue (alkaline)

Question 3

how do you test for chloride ions?

Answer 3

add nitric acid followed by silver nitrate solution
a white precipitate will form
Ag^+ (aq) + Cl^- (aq) -> AgCl (s)

Question 4

how do you test for bromide ions?

Answer 4

add nitric acid followed by silver nitrate solution
a cream precipitate will form
Ag^+ (aq) + Br^- (aq) -> AgBr (s)

Question 5

how do you test for iodide ions?

Answer 5

add nitric acid followed by silver nitrate solution
a yellow precipitate will form
Ag^+ (aq) + I^- -> AgI (s)

Question 6

how do you test for carbonate ions?

Answer 6

add dilute acid to a solution containing the carbonate ion
effervescence will be observed

Question 7

how do you test for ammonium ions?

Answer 7

add dilute sodium hydroxide to a solution containing the ammonium ion and gently warm the reaction mixture
a pungent gas will form which turns red litmus paper blue