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CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics

Problem

298\,\text{K}

. 1.

H_{2}(g) + \tfrac{1}{2}O_{2}(g) \rightarrow H_{2}O(g) \qquad \Delta H_{1} = -242\,\text{kJ}

H_{2}O(l) \rightarrow H_{2}O(g) \qquad \Delta H_{\text{vap}} = +44\,\text{kJ}

CO(g) + \tfrac{1}{2}O_{2}(g) \rightarrow CO_{2}(g) \qquad \Delta H_{3} = -283\,\text{kJ}

A student wants the enthalpy change for

CO(g) + \tfrac{1}{2}O_{2}(g) + H_{2}(g) \rightarrow CO_{2}(g) + H_{2}O(l)

The student adds

\Delta H_{3}

and

\Delta H_{1}

and reports

\Delta H_{\text{rxn}} = -525\,\text{kJ}

. Which of the following is the correct value for

\Delta H_{\text{rxn}}

? (a)

-481\,\text{kJ}

(b)

-613\,\text{kJ}

(c)

-569\,\text{kJ}

(d)

-525\,\text{kJ}