Select the correct answer.

Consider this reaction:
[tex]\[ CaCO_3(s) \rightarrow CaO(s) + CO_2(g) \][/tex]

What could be done to increase the rate of decomposition of \( CaCO_3 \)?

A. add \( CO_2 \)

B. remove \( CO_2 \)

C. decrease the pressure

D. decrease the temperature

E. increase the temperature



Answer :

To determine how to increase the rate of decomposition of \( CaCO_3 \) in the reaction:

[tex]\[ CaCO_3(s) \rightarrow CaO(s) + CO_2(g) \][/tex]

we need to consider the factors that influence reaction rates. Here’s a detailed step-by-step examination of each option:

Step 1: Analyze the effect of adding \( CO_2 \) (Option A)
- Adding \( CO_2 \) will shift the equilibrium of the reaction to the left, favoring the formation of \( CaCO_3 \). This would decrease the rate of decomposition, not increase it.

Step 2: Analyze the effect of removing \( CO_2 \) (Option B)
- Removing \( CO_2 \) would shift the reaction equilibrium to the right, thereby increasing the amount of \( CaCO_3 \) decomposed into \( CaO \) and \( CO_2 \). However, this does not directly affect the rate of the reaction, but rather the extent to which the reaction can proceed.

Step 3: Analyze the effect of decreasing the pressure (Option C)
- Decreasing the pressure generally affects reactions where gaseous reactants or products are involved. For the decomposition of \( CaCO_3 \), which produces \( CO_2 \), decreasing the pressure would favor the production of more \( CO_2 \), thus potentially increasing the decomposition rate. However, this is not the most impactful factor compared to temperature changes.

Step 4: Analyze the effect of decreasing the temperature (Option D)
- Decreasing the temperature would typically slow down the rate of most reactions, including the decomposition of \( CaCO_3 \). Lower temperatures reduce the kinetic energy of molecules, leading to fewer effective collisions.

Step 5: Analyze the effect of increasing the temperature (Option E)
- Increasing the temperature generally increases the rate of most chemical reactions. Higher temperatures provide more energy to the reactant molecules, increasing the number of collisions with sufficient energy to overcome the activation energy barrier. This will hasten the decomposition of \( CaCO_3 \).

Given these analyses:

- The best way to increase the rate of decomposition of \( CaCO_3 \) is to increase the temperature.

Thus, the correct answer is:

E. increase the temperature

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