Question 2B
G is a mixture of two salts, one of which is a sodium salt. Carry out the following exercises on G. Record your observations and identify any gas(es) evolved. State the conclusions you draw from the results of each test.
- Put G into a beaker and add about 10 cm3 of distilled water. Stir the mixture and filter. Keep both he filtrate and residue. Test the filtrate with litmus paper.
- To about 2 cm3 of the filtrate, add dilute HCl followed by few drops of BaCl(aq).
- (i) Place about half of the residue from 2(a) in a boiling tube and add about 10 cm3 of dilute HNO3.
(ii) To about 2 cm3 portions of the clear solution from 2(c)(i), add dilute NaOH in drops and then in excess.
(iii) To another 2 cm3 portions of the solution, add dilute HCl.
[22 marks]
Observation
In part (a), majority of the candidates were able to write the observations and inferences correctly.
In part (b), some candidates did not follow the instructions. So, they lost marks to wrong observations and inferences.
In part (c), majority of the candidates could not deduce correct inferences from observations made.
The expected answers include:
