4) Testing For Cations: Grp2, NH4^+

Question 1

Describe the method of adding dilute sodium hydroxide

Answer 1

1) place 10 drops of 0.1m metal on sol in test tube
2) add 10 drops of 0.6 M NaOH sol
3) continue to add NaOH sol drop wise with gentle shaking until in excess

Question 2

What is the result with

1) Mg(OH)2,
2) Ca(OH)2,
3) Ba(OH)2?

Answer 2

1) Forms white ppt = insoluble
2) Forms white ppt= partially soluble
3) NVC= soluble

Question 3

Describe the method for testing for ammonium ions

Answer 3

1) place 10drops of 0.1M of NH4Cl in test tube
2) place 10 drops of 0.4 M NaOH sol and shake mixture
3) warm mixture gently with water bath.
4) test the fumes released from the mixture by holding a piece of red litmus paper in mouth of test tube
Result= alkaline ammonia gas turns red litmus paper blue

Question 4

What are the results when you add sulfate ions to

1) Barium?
2) magnesium

Answer 4

1) white ppt

2) NVC