IGCSE Chemistry: Specimen Questions with Answers 109 - 109 of 240

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Question 109

Question

MCQ▾

Calcium carbonate reacts with hydroelectric acid to form carbon dioxide.

Which changes would slow this reaction down?

1. Decreasing the concentration of hydroelectric acid

2. Decreasing the particle size of calcium carbonate

3. Decreasing the temperature

Choices

Choice (4)

a.

b.

c.

d.

Answer

d.

Explanation

Correct option is D i.e.. because the rate of reaction increases with concentration because when the acid is more concentrated, there are more acid particles in a given volume. This means there is a better chance of a successful collision occurring. If you increase the temperature, the rate of reaction will increase. This is because at low temperatures the particles don՚t have as much energy, but when they are heated they take in energy which makes them move faster and collide more often. This means the collisions also have more energy, which makes more of the collisions successful. This is why as you increase the temperature the rate of reaction increases. And the decreasing the particle because is eventually soluble in HCl. As shown in figure.

The CaCO3 + HCl
Image Showing the CaCO3 + HCl

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