Question

2so₂(g) + o₂(g) → 2so₃(g) + 199. kj
your answer
part 1 of 2
is this reaction endothermic or exothermic? select the single best answer.
endothermic
exothermic
part: 1 / 2
part 2 of 2
calculate the amount of heat released when 0.490 moles of sulfur dioxide are used in the reaction. be sure your answer has the correct number of significant figures.
kj

Explanation:

Step1: Analyze the reaction stoichiometry

From the reaction \(2\text{SO}_2(g) + \text{O}_2(g)
ightarrow 2\text{SO}_3(g) + 199.\text{ kJ}\), 2 moles of \(\text{SO}_2\) release 199. kJ of heat.

Step2: Set up the proportion for 0.490 moles of \(\text{SO}_2\)

Let \(x\) be the heat released for 0.490 moles of \(\text{SO}_2\). The proportion is \(\frac{199.\text{ kJ}}{2\text{ mol}}=\frac{x}{0.490\text{ mol}}\).

Step3: Solve for \(x\)

Cross - multiply: \(x=\frac{199.\text{ kJ}\times0.490\text{ mol}}{2\text{ mol}}\).
Calculate: \(x = \frac{97.51\text{ kJ}\cdot\text{mol}}{2\text{ mol}} = 48.755\text{ kJ}\approx48.8\text{ kJ}\) (rounded to three significant figures as 0.490 has three significant figures).

Answer:

\(48.8\)