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The values of heat of formation of SO₂ and SO₃ are -298.2 kJ and -98.2 kJ. The heat of formation of the reaction SO₂ + 1/2O₂ → SO₃ will be
- -200 kJ
- -356.2 kJ
- +200 kJ
- -396.2 kJ
Correct answer: -200 kJ
Solution
To find the heat of formation of the reaction SO₂ + 1/2O₂ → SO₃, we need to use the heat of formation of SO₂ and SO₃. The heat of formation of SO₂ is -298.2 kJ, and the heat of formation of SO₃ is -98.2 kJ. Therefore, the heat of formation of the reaction SO₂ + 1/2O₂ → SO₃ is -98.2 - (-298.2) = 200 kJ. However, the question asks for the heat of formation, which is the negative of the heat of reaction. Therefore, the heat of formation is -200 kJ.
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