The heat of formation of CO(g) and CO_2(~g) are Δ H=-110 and Δ H=-393 ~kJ ~mol^ -1 respectively. What is the heat of reaction (Δ H) (in kJ mol^ -1 ) for the following reaction? CO(g)+(1)/(2) O_2(~g) CO_2(~g)

Correct answer: C. -283 aligned & C+(1)/(2) O_2 CO, Δ H=-110 kJ mol^ -1 (i) & C+O_2 CO_2, Δ H=-393 kJ mol^ -1 & (ii) aligned On subtracting Eq. (i) from Eq. (ii), we get aligned CO & +(1)/(2) O_2 CO_2 Δ H & =393-(-110) & =-283 kJ mol^ -1 aligned

JIPMER 2009

Exam: JIPMER
Year: 2009
Subject: Chemistry
Chapter: Thermodynamics (C)

JIPMER 2009 · Chemistry · Thermodynamics (C)

The heat of formation of CO(g) and CO_2(~g) are Δ H=-110 and Δ...

The heat of formation of

\mathrm{CO}(\mathrm{g})

and

\mathrm{CO}_2(\mathrm{~g})

are

\Delta H=-110

and

\Delta H=-393 \mathrm{~kJ} \mathrm{~mol}^{-1}

respectively. What is the heat of reaction

(\Delta H)

(in

\mathrm{kJ} \mathrm{mol}^{-1}

) for the following reaction?

\mathrm{CO}(\mathrm{g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \longrightarrow \mathrm{CO}_2(\mathrm{~g})

Options

A-504
B-142.5
C-283
D504

Correct answer

C. -283

Step-by-step solution

\begin{aligned} & \mathrm{C}+\frac{1}{2} \mathrm{O}_2 \longrightarrow \mathrm{CO}, \Delta H=-110 \mathrm{ kJ} \mathrm{ mol}^{-1} \ldots \text{ (i) } \\ & \mathrm{C}+\mathrm{O}_2 \longrightarrow \mathrm{CO}_2, \quad \Delta H=-393 \mathrm{ kJ} \mathrm{ mol}^{-1} \\ & \ldots \text{ (ii) } \end{aligned}

On subtracting Eq. (i) from Eq. (ii), we get

\begin{aligned} \mathrm{CO} & +\frac{1}{2} \mathrm{O}_2 \longrightarrow \mathrm{CO}_2 \\ \Delta H & =393-(-110) \\ & =-283 \mathrm{ kJ} \mathrm{ mol}^{-1} \end{aligned}

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