Chemistry Paper 3A WASSCE (SC), 2016

Question 2A

                C is a mixture of two salts, containing one action and two anions.
Carry out the following exercises on C. Record your observations and identify any gas(es) evolved.  State the conclusion you draw from the result of each test.

(a)        Put all of C in a beaker and add about 10 cm3 of distilled water.
Stir well and filter.  Keep the filtrate and the residue.

(b)        To about 2 cm3 of the filtrate, add few drops of Ag.NO3(aq) followed by                 
HNO3(aq). Add excessNH3(aq)  to the resulting mixture.

(c)        (i)        Put all of the residue into a clean test tube and add about 5 cm3 of      
HNO3(aq).

(ii)        To about 2 cm3 of the solution from 2(c)(i), add NaOH(aq) in drops and then in excess .

(iii)       To another 2cm3 of the solution from 2(c)(i), add NH3(aq) in drops and then in excess.

Observation

 

Majority of the candidates could not correspond the observations to inferences.  In           addition, majority of them carried out the tests on a solid sample instead of solutions. 
            Some candidates lost marks due to wrong charges on ions.

 Expected answers include: