PAG 04 - Qualitative Analysis Of Ions

Question 1

Describe chemical test for halide ions

Answer 1

Add dilute nitric acid to react with carbonate ions

So no Ag2CO3 forms (white solid)

Add silver nitrate. PPT forms:
- white: AgCl (soluble in dilute ammonia)
- cream: AgBr (soluble in conc ammonia)
- yellow: AgI (insoluble in ammonia)

Question 2

How can SO4^2- be identified

Answer 2

Add barium nitrate

White ppt (BaSO4) will form if sulfate ions are present

This ppt is insoluble in excess dilute strong acids

Question 3

Describe chemical test used to detect CO3^2- and HCO3^-

Answer 3

Add aq acid

If either ion is present bubbles of CO2 will be released

Test gas by bubbling it through limewater via a delivery tube. If its CO2, limewater will turn cloudy

Question 4

What are solubilities of 1st 3 group 2 metals (Mg, Sr, Ba) in sulfate solution

Answer 4

Mg - soluble

Sr - Insoluble

Ba - insoluble

Question 5

What are solubilities of 1st 3 group 2 metals (Mg, Sr, Ba) in chromate solution

Answer 5

Mg - soluble

Sr - soluble

Ba - insoluble