Given: S (s)+ O₂ (g)→ SO₂ (g)ΔH° = -296.1 kJ 2 SO₃ (g)→ 2 SO₂ (g)+ O₂ (g)ΔH° = 198.2 kJ Find ΔH° for : 2 S(s)+ 3 O₂(g)→ 2 SO₃(g)

Question

Quizplus · Accepted Answer

To solve this problem, we need to use Hess's Law, which states that the enthalpy change for a reaction is the same whether it occurs in one step or is broken down into a series of steps. In other words, we can use the enthalpy changes for the given reactions to find the enthalpy change for the desired reaction. First, we need to manipulate the given reactions to match the desired reaction. We can see that the second reaction has two of the desired product, but we need to get rid of the extra O₂(g). We can do this by reversing the first reaction and doubling it: 2 SO₂ (g) → 2 S (s) + 2 O₂ (g) ΔH° = +296.1 kJ Now we can add these two manipulated reactions together to get the desired reaction: 2 S (s) + 3 O₂ (g) → 2 SO₃ (g) ΔH° = -790.4 kJ Therefore, the answer is A, -790.4 kJ.

Given: S (S)+ O2 (G)→ SO2 (G)ΔH° = -296

Given: S (S)+ O₂ (G)→ SO₂ (G)ΔH° = -296