Question

the thermochemical equation for the reaction of carbon dioxide with sulfur dioxide is shown below. how can the reaction be described?

$$\ce{co_{2}(g) + 2so_{2}(g) + 1104\\ kj -> cs_{2}(g) + 3o_{2}(g)}$$

\\(\bigcirc\\) a. it has a low activation energy.
\\(\bigcirc\\) b. it is endothermic.
\\(\bigcirc\\) c. it has a high activation energy.
\\(\bigcirc\\) d. it is exothermic.

Explanation:

1. Recall the definitions of endothermic and exothermic reactions:

• In a thermochemical equation, if energy (in the form of heat, here given as kJ) is on the reactant side, the reaction absorbs energy from the surroundings, which is characteristic of an endothermic reaction.
• If energy is on the product side, the reaction releases energy (exothermic).
• Activation energy (the energy needed to start a reaction) is not indicated by the position of energy in the thermochemical equation (options A and C are about activation energy, which can't be determined from this equation).

1. Analyze the given equation: \( \ce{CO_2(g) + 2SO_2(g) + 1104\ kJ

ightarrow CS_2(g) + 3O_2(g)} \)

• The 1104 kJ is on the reactant side, meaning the reaction requires energy input. So it is endothermic (eliminating D, as exothermic releases energy). Activation energy details aren't provided by this equation, so A and C are incorrect.

Answer:

B. It is endothermic.