2.38 describe the tests for these anions:

i Cl-, Br- and I- using dilute nitric and silver nitrate solution

Testing for Halide ions by precipitation. Method:

  1. Add dilute nitric acid
  2. Add dilute silver nitric acid
  3. Check the precipitate colour Screen Shot 2016-07-21 at 2.09.32 PM.png

 

 

 

ii SO4 2- (sulphate ions) using dilute hydrochloric acid and dilute barium chloride solution

Method:

  1. Add dilute hydrochloric acid
  2. Add dilute barium chloride
  3. Ba  2+ (aq) + SO4 2 (l)- –> BaSO4 2- (s)
  4. Barium sulfate precipitate is white – hence the solid symbol at the end

iii CO3 2- , using dilute hydrochloric acid and identifying the carbon dioxide evolved

Method:

  1. Add and acid to react with the solution under test
  2. Collect the gas given off by collecting in a test tube
  3. Test with lime water – if it goes milky, then there is presence of carbonate ions
  • Carbonate + acid –> salt + water + carbon dioxide
  • CO3 2- (aq) + 2H+ + (aq) –> CO2 (g) + H2O (l)
  • It’s the hydrogen ions (H+) which make the solution acidic- therefore causing the solution to bubble and produce carbonate bubbles
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