Enthalpy of combustion of carbon to carbon dioxide is −390.0 kJ mol⁻¹. The amount of heat released when 35.0 g of CO2 is formed from the reaction of carbon and dioxygen gas, is:
310 kJ
490 kJ
245 kJ
700 kJ
The combustion of carbon to form carbon dioxide is given by the reaction: C(s) + O₂(g) → CO₂(g); \Delta cH = −390.0 kJ mol⁻¹. This means that when 1 mole of CO₂ (which has a molar mass of 44 g) is formed, 390.0 kJ of heat is released. We need to find the heat released when 35.0 g of CO₂ is formed. Number of moles of CO₂ in 35.0 g = 35.0 g / 44 g mol⁻¹. Amount of heat released = (35.0 / 44) × 390.0 kJ = 310.22 kJ ≈ 310 kJ.
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