cameroon gce advanced level 2023 engineering science 3

Here is the extracted text from the newly uploaded chemistry practical sheet (image_096eeb.jpg):

OBSERVATION / DATA / CALCULATIONS.

1. Complete table 1 bellow.

Experiment	Volume of Na2​S2​O3(aq)​/cm3	Volume of H2​O(l)​/cm3	Volume of HCl(aq)​/cm3	Time / s
A	10	30	10
C	10	20	20
E	10	10	30

2. State your observation in procedure (4) above …………………………………………………………………………….

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3. Write the balanced chemical reaction between hydrochloric acid and sodium thiosulphate ……………………………………………………………………………………………………………………………………………………

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4. Write down the name and formula of the product that causes the cross to become invisible

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5. Give a reason why water is added to the reaction mixture in experiments A to E.

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6. State TWO factors that can influence the rate of the reaction above.

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7. In which experiment (A, C or E) is the reaction rate the highest? ……………………………………………………

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8. Use the collision theory to explain the difference in reaction rate between experiments A and C

june 2021

• Paper 3