Question

When the enthalpy of combustion of carbon to carbon dioxide is - 360 kJ mol^-1, then the enthalpy change for the formation of 18 g of CO₂ from carbon and dioxygen at the same temperature in kJ will be ______.

Options

• - 125.22

• 125.22

• - 147.27

• 147.27

Answer 1

When the enthalpy of combustion of carbon to carbon dioxide is - 360 kJ mol^-1, then the enthalpy change for the formation of 18 g of CO₂ from carbon and dioxygen at the same temperature in kJ will be - 147.27.

Explanation:

The reaction involved in combustion is

\[\ce{C + O2 -> CO2}\], ΔH = - 360 kJ mol^-1

Molar mass of CO₂ = 44

and 44g of formation of CO₂ gives heat = - 360 kJ

So, 18 g of formation of CO₂ gives heat = `(- 360 xx 18)/44`

= - 147.27 kJ