FC15: Qualitative Analysis

Question 1

How do you test for Chloride ions

Answer 1

Add aqueous silver nitrate,
If Cl- is present, a white ppt of AgCl forms that is soluble in both dilute and conc. aqueous ammonia

Question 2

How do you test for Bromide ions

Answer 2

Add aqueous silver nitrate,
If Br- is present, a cream ppt of AgBr forms that is only soluble in conc. aqueous ammonia not dilute ammonia

Question 3

How do you test for Iodide ions

Answer 3

Add aqueous silver nitrate,
If I- is present, a yellow ppt of AgI forms that is insoluble in both conc. and dilute aqueous ammonia

Question 4

How do you test for sulfate ions

Answer 4

Add aqueous barium ions e.g. Ba(NO3)2, BaCl2
If sulfate ions are present, a white ppt of BaSO4 forms

Question 5

How do you test for carbonate ions

Answer 5

Add dilute inorganic acid e.g. HNO3
If carbonate ions are present, effervescence occurs due to carbon dioxide being formed

Question 6

List white precipitates

Answer 6

AgCl
Ag2CO3
Ag2SO4
BaSO4
BaCO3

Question 7

How do you test for ammonium ions

Answer 7

Add aqueous NaOH and then warm the mixture
If a vapour that turns damp red litmus indicator paper blue, then ammonia gas being formed from ammonium ions in solution

Question 8

What is the order for testing for ions and how can you remember it

Answer 8

CaSH
Ca - carbonates
S - sulfates
H - halides
Ammonium