Enthalpy of combustion of carbon to carbon dioxide is -390\ kJ/mol . What is the amount of heat released when 35\ g of carbon dioxide is formed from the reaction of carbon and dioxygen gas?

Question

Quantrex Academy · Accepted Answer

Correct answer: B. 310\ kJ

The combustion reaction of carbon is given by:

C(s) + O_2(g) \rightarrow CO_2(g)

The enthalpy of combustion is

\Delta H = -390\ \text{kJ/mol}

. This means

390\ \text{kJ}

of heat is released when

1\ \text{mol}

of

CO_2

is formed.

Molar mass of

CO_2 = 12 + 2 \times 16 = 44\ \text{g/mol}

Number of moles in

35\ \text{g}

of

CO_2 = \dfrac{35}{44}\ \text{mol}

Amount of heat released

= \dfrac{35}{44} \times 390\ \text{kJ} = 310.22\ \text{kJ} \approx 310\ \text{kJ}

Answer:

310\ \text{kJ}

Enthalpy of combustion of carbon to carbon dioxide is -390\ kJ/mol...

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