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Qualitative analysis questions

Qualitative analysis questions | form four Chemistry

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# Question
1

Sample V is a simple salt containing one cation and one anion. Carry out the experiments described in the experimental table. Carefully record your observations and make appropriate inferences to identify the anion and cation present in sample V.

Experimental table

S/N Experiment Observation Inference
(a) Appearance of sample V.    
(b) To a small portion of dry sample in a test tube add enough amount of distlled water, warm if insoluble.    
(c) To a small portion of a dry sample in test tube add concentrated H2SO4 acid.    
(d) To a small portion of a dry sample in a test tube heat gently and then strongly until no further change.    
(e) Put a small portion of sample in a dry test tube followed by dillute HCl acid. Divide the solution into three portions.    
(i) To one portion add NaOH till in excess.    
(ii) To the second portion add a few drops of MgSO4 solution. If no precipitate warm the contents.    
(iii) To the third portion add ammonia solution till in excess.    

Conclusion

  1. (i)The cation in sample V is ______ and anion is ______

          (ii) The name of sample V is ________

          (iii) The chemical formula of sample V is __________

  1. With the aid of a balanced ionic equation, explain the effect of the dilute HCl to the sample V in experiment ( e ).

Practical
2

Sample N  is a simple salt containing one cation and one anion. Carefully carry out all the experiments described in Table 2. Record all your observations and make appropriate inferences to identify the cation and anion present in sample N.

Table 2.

S/N Experiment Observation Inference
(a) Appearance of the solid  sample N.    
(b) Put a spatulaful of the sample N in a test tube and heat.    
(c) Add dilute hydrochloric acid to the solid sample N.    
(d) Perform flame test on the sample.    
(e) Dissolve the sample in water. Divide the resulting solution into two portions.    
(i) Add sodium hydroxide to the first portion.    
(ii) Add few drops of magnesium sulphate solution to the second portion, then warm.    

Conclusion

  1. The cation is ____ and the anion is ____
  2. The sample N is ______
  3. Write the chemical equations (with state symbols) to show reactions which took place in the experiments (b) and ( c ).
  4. Describe three uses of sample N.

Practical