Chemistry

Problem

A laboratory manual provides these enthalpy data (298 K): 1.

N_{2}O_{4}(g)\rightarrow 2NO_{2}(g)\qquad \Delta H_{1}= +58\,\text{kJ}

NO_{2}(g)+CO(g)\rightarrow NO(g)+CO_{2}(g)\qquad \Delta H_{2}= -227\,\text{kJ}

N_{2}(g)+O_{2}(g)\rightarrow 2NO(g)\qquad \Delta H_{3}= +182\,\text{kJ}

CO(g)+\tfrac{1}{2}O_{2}(g)\rightarrow CO_{2}(g)\qquad \Delta H_{4}= -283\,\text{kJ}

A student wishes to find the enthalpy change for

N_{2}O_{4}(g)+CO(g)\rightarrow N_{2}(g)+CO_{2}(g)+O_{2}(g)

The student combines Equations 1 and 2 as written and subtracts Equation 3, claiming

\Delta H_{\text{rxn}} = -351\,\text{kJ}.

After carefully evaluating the steps, which of the following is the correct value of

\Delta H_{\text{rxn}}

? a)

-351\,\text{kJ}

-408\,\text{kJ}

-146\,\text{kJ}

-292\,\text{kJ}