Form 4 Chemistry Study Notes

ITILIMA DISTRICT COUNCIL FORM FOUR MOCK EXAMINATION 032/2 | CHEMISTRY 2A (ACTUAL PRACTICAL)

 

Time: 2:30 Hours Thursday, 23rd July 2020 a.m

Instructions

1. This paper consists of two (2) questions. Answer all questions.

2. Each question carries 25 marks

The following constants may be used:

Atomic masses: C=12, O=16, Mg=24, Al=26 S=32, Cl=35.5 H=1


Tangazo



1litre = 1dm3 =1000cm3

Questions

1. You are provided with the following;

Solution SS: containing 1.825 g of HCl per dm3 of the solution.

Solution YY: containing 0.5 g of XOH in 250 cm3 of the solution.

Methyl orange indicator (MO).

Procedures

Put solution SS in the burette. Pipette 20 cm3 or 25 cm3 of solution YY into a titration flask.

Add two drops of MO indicator. Titrate solution YY against solution SS from the burette

until a colour change is observed. Repeat the procedure to obtain three more readings and

record your results in a tabular form.

Questions

(a) (i)……cm3 of solution YY required ..…cm3 of solution SS for complete neutralization.

(ii) The colour change at the end point was from ____________ to _____________

(b) Write a balanced chemical equation for the reaction between solution YY and SS

(c) Calculate the;

(i) Molarity of SS

(ii) Molarity of YY

(iii) Molar mass of XOH

(iv) Atomic mass of X in XOH

(d) Name element X

 

 

 

 

 

 

2. Sample D is a simple salt containing one cation and one anion. Carry out the experiments

described in the experimental table. Careful record your observations and make appropriate



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inferences to identify the anion and cation present in sample D

Experimental table

S/N

Experiment

Observation

Inference

(i)

Appearance of sample D

   

(ii)

To a small portion of a dry sample in a test tube add enough amount of distilled water, warm if insoluble

   

(iii)

To a small portion of a dry sample in a test tube add concentrated H2SO4 acid.

   

(iv)



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To a small portion of a dry sample in a dry test tube, heat gently and then strongly until no further change

   

(v)

Put a small portion of sample in a dry test tube followed by dilute HCl acid. divide the solution into three portions

   

(vi)

To one portion add NaOH till in excess

   

(vii)

To the second portion add MgSO4 solution. If no precipitate warm the contents.

   

(viii)

To the third portion add ammonia solution till in excess

   

 

Conclusion

(i) The cation in sample D is _________and anion is _________

(ii) The name of sample D is ____________

(iii) The chemical formula of sample D is ____________

(iv) With the aid of a balanced ionic equation, explain the effect of the dilute HCl to the sample D



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in experiment (e)



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