Question

Syngas can be burned directly or converted to methanol. Calculate $\Delta H°$for the reaction

$CO\left(g\right)+2H_2\left(g\right)\to C{H}_{3}OH\left(l\right)$

Short answer

The $\Delta H°$ for the reaction is -128.0 kJ.

Step-by-step solution

Enthalpy of formation of substance

The enthalpy of formation of the substance present in the reaction is,

$$\begin{gathered} \Delta H_f^0 of CO\left(g\right)=-111.0kJ \\ \Delta H_f^0 of H_2\left(g\right)=0kJ \\ \Delta H_f^0 of C{H}_{3}OH\left(g\right)=-239.0kJ \end{gathered}$$

Determination of ΔH° for the reaction

The $\Delta H^o$for the reaction is,

$$\begin{gathered} \Delta H^o=\Delta H_f^o\left(product\right)-\Delta H_f^o\left(reactant\right) \\ \Delta H^o=\Delta H_f^o\left(C{H}_{3}OH\right)-\left[\Delta H_f^o\left(CO\right)+2\times \Delta H_f^o\left(H_2\right)\right] \\ \Delta H^o=\left(-239.0kJ\right)-\left[\left(-111.0kJ\right)+\left(2\times 0\right)\right] \\ \Delta H^o=-128.0kJ \end{gathered}$$

Thus, $\Delta H^o$for the reaction is -128.0 kJ.