Question

Enthalpy of combustion of carbon to $ C{{O}_{2}} $ is $ -393.5\,kJ\,mo{{l}^{-1}}. $ The heat released upon formation of $35.2\, g$ of $ C{{O}_{2}} $ from carbon and dioxygen gas is (molar mass of $ C{{O}_{2}}=44\,g\,mo{{l}^{-1}} $ )

• A. 3.148 kJ
• B. 31.48 kJ
• C. 314.8 kJ
• D. 3148 kJ

Answer 1

Answer: (C)

$ C(s)+{{O}_{2}}(g)\xrightarrow[{}]{{}}\underset{44\,g}{\mathop{C{{O}_{2}}(g);}}\, $
$ \Delta H=-393.5\text{ }kJ\text{ }mo{{l}^{-1}} $
Heat released in the formation of
$ 44\text{ }g\,C{{O}_{2}}=393.5\text{ }kJ $
$ \therefore $ Heat released in the formation of
$ 35.2\text{ }g\,C{{O}_{2}}=\frac{393.5\,kJ\times 35.2\,g}{44\,g} $
$ =314.8\text{ }kJ $