Calculate the change in enthalpy when 52.0 g of solid chromium at 25°C and 1 atm pressure is oxidized.(ΔH°_f for Cr₂O₃(s) is -1135 kJ/mol.)
4Cr(s) + 3O₂(g) → 2Cr₂O₃(s)

Question

Calculate the change in enthalpy when 52.0 g of solid chromium at 25°C and 1 atm pressure is oxidized.(ΔH°_f for Cr₂O₃(s)is -1135 kJ/mol.) 4Cr(s)+ 3O₂(g)→ 2Cr₂O₃(s)

Quizplus · Accepted Answer

The reaction shows that 4 moles of Cr produce 2 moles of Cr2O3. The given ΔH°f for Cr2O3 is -1135 kJ/mol, which is for 1 mole. For 2 moles, it would be -2270 kJ. Since 52.0 g of Cr is 1 mole (given the atomic mass of Cr is approximately 52 g/mol), the reaction involves 1 mole of Cr, which is 1/4 of the reaction. Therefore, the enthalpy change for 52.0 g of Cr would be 1/4 of -2270 kJ, which is -568 kJ.

Calculate the Change in Enthalpy When 52