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Form 4 Chemistry Paper 3 End of Term 2 Exams 2021

Class: Form 4

Subject: Chemistry

Level: High School

Exam Category: Form 4 End Term 2 Exams

Document Type: Pdf

    

Views: 957     Downloads: 29

Exam Summary

233/3
CHEMISTRY
PAPER 3
END OF TERM 2 EXAM 2021

QUESTION 1
• You are provided with solution K and L
• Solution K is 1M H2SO4
• Solution L contains 8.7g of the hydroxide of metal M {with formulae MOH] in 600cm3 of the solution
• You are required to carry out the experiment to determine;
i. Concentration of solution L
ii. R.A.M of metal M
Procedure
1. Measure 75cm3 of solution K and put into a clean 250cm3 volumetric flask and add distilled water up to the mark
-label this solution W
2. Fill a clean burette with solution W
3. Pipette 25cm3 of solution L into a clean conical flask and add 2 drops of phenolphthalein indicator
4. Titrate the solution W in the burette against solution L in the conical flask and record the results in the table below
5. Repeat {3} and {4} above as you fill the table below.

Capture1.JPG [4mks]
{a} Calculate the;
{i} Average volume of solution W used [1mk]


{ii} Concentration of solution W [1mk]


{iii} Number of moles of solution W that reacted with each 25cm3 portion of solution L {2mks]


{b} Calculate the;
{i} Number of moles of the metal hydroxide {MOH} in solution L that reacted with each portion of solution W [2mks]


{ii} Concentration of solution L [1mk]


{iii} Number of moles of the metal hydroxide [MOH]in 600cm3 of solution L [2mks]


{iv} R.A.M of metal M [2mks]
[0=16, H=1]

QUESTION 2
You are provided with solution N and P
• Solution N is 2M HCl
• Solution P is 0.16M sodium thiosulphate
• You are required to carry out the experiment below to determine how concentration affects the rate of reaction between HCl and sodium thiosulphate solutions

PROCEDURE

1. Fill a clean burette with solution P.
Measure 25cm3 of the solution P from the burette into a clean 100cm3 glass beaker and place on a white piece of paper with a cross[x] marked on it
2. Add 10cm3 of solution N into it and immediately start a stop watch and note the time taken for the cross beneath the mixture to become invisible
3. Clean the 100cm3 beaker and measure into it 20cm3 of solution P form the burette, and add 5cm3 of distilled water into the solution solution
4. Repeat step [2] above and note the time taken for the cross to become invisible
5. Repeat the experiment using volumes indicated on the table below and as you record the results (4mks)
Capture2.JPG
[a] plot a graph of 1t against volume of solution P on the grid provided [3mk]
Capture3.JPG
{b} From the graph
{i} Determine the time taken for the cross to become invisible when 12.5cm3 of solution P is used [2mks]


{ii} Explain the effect of concentration on the rate of reaction between HCl and sodium thiosulphate solution [2mks]


QUESTION 3
• You are provided with solids Q and R
• You are required to carry out the tests below as you record your observations and inferences
(i) SOLID Q
-Add about 5cm3 of distilled water to solid Q, shake the mixture thoroughly for a while and then filter it
NOTE: Retain both the filtrate and the residue for the tests below
Capture4.JPG
Capture5.JPG
Capture6.JPG

 

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