Question

The heat of combustion of carbon to ${CO_2}$ is ${- 393.5 \, kJ/mol}$. The heat released upon formation of 35.2 g of ${CO_2}$ from carbon and oxygen gas is:

• A. - 630 kJ
• B. - 3.15 kJ
• C. - 315 kJ
• D. #ERROR!

Answer 1

Answer: (C)

- 315 kJ

Answer 2

Formation of ${CO_2}$ from carbon and dioxygen gas can be represented as ${C(s) + O_{2(g)} -> CO_{2(g)} ; \Delta_fH = - 393.5 \; kJ \; mol^{-1}}$ (1 mole = 44 g) Heat released on formation of 44 g ${CO_2}$ $= -393.5 \; kJ \; mol^{-1}$ $= \frac{-393.5 \; kJ \; mol^{-1}}{44g} \times 35.2 g$ $= - 315 \; kJ$