The thermochemical equation for the dissociation of hydrogen gas into atoms may be written as

${\mathrm{H}}_2\to 2\mathrm{H}; \mathrm{\Delta H}=436 \mathrm{kJ}$

What is the ratio of the energy yield on combustion of hydrogen atoms to steam to the yield on combustion of an equal mass of hydrogen molecules to steam? ${\mathrm{\Delta H}}_{\text{combustion }}\text{ for }{\mathrm{H}}_2=-241.81 \mathrm{kJ}$

Answer correct up to one significant value.

Calculate the value of $\log {\mathrm{K}}_{\mathrm{p}}$ for the reaction: ${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\rightleftharpoons 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$ at $25°\mathrm{C}$. The standard enthalpy of formation of ${\mathrm{NH}}_3\left(\mathrm{g}\right)$ is $-46 \mathrm{kJ}$ and the standard entropies of ${\mathrm{N}}_2, {\mathrm{H}}_2$ and ${\mathrm{NH}}_3$ gases are $191, 130, 192 {\mathrm{JK}}^{-1} {\mathrm{mol}}^{-1}$, respectively. 

Round off your answer to the nearest integer.

In a fuel cell, methanol is used as a fuel and oxygen gas is used as an oxidizer. The reaction is ${\mathrm{CH}}_3\mathrm{OH}\left(\mathrm{l}\right)+\frac{3}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{CO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$.

At $298 \mathrm{K}$, the standard Gibbs energies of the formation for ${\mathrm{CH}}_3\mathrm{OH}\left(\mathrm{l}\right), {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$ and ${\mathrm{CO}}_2\left(\mathrm{g}\right)$ are $-166.2,-237.2$ and $-394.4 \mathrm{kJ} {\mathrm{mol}}^{-1}$, respectively. If the standard enthalpy of combustion of methanol is $-726 \mathrm{kJ} {\mathrm{mol}}^{-1}$, the efficiency of the fuel cell will be:

A monoatomic gas, a diatomic gas and a triatomic gas are mixed, taking one mole of each. ${\mathrm{C}}_{\mathrm{p}}/{\mathrm{C}}_{\mathrm{v}}$ for the mixture is:

Find the $\mathrm{\Delta H}$at $358 \mathrm{K}$ for the reaction, ${\mathrm{Fe}}_2{\mathrm{O}}_3 \left(\mathrm{s}\right)+ 3{\mathrm{H}}_2 \left(\mathrm{g}\right)\to 2\mathrm{Fe} \left(\mathrm{s}\right) +3{\mathrm{H}}_2\mathrm{O} \left(l\right)$.

Given that $\mathrm{\Delta H} \text{at} 298 \mathrm{K}=-33.29 \mathrm{kJ} {\mathrm{mol}}^{-1}$ and $\mathrm{Cp}$for ${\mathrm{Fe}}_2{\mathrm{O}}_3 \left(\mathrm{s}\right),$ $\mathrm{Fe} \left(\mathrm{s}\right),{\mathrm{H}}_2\mathrm{O} \left(l\right), \text{and} {\mathrm{H}}_2 \left(\mathrm{g}\right)$are $103.8, 25.1, 75.3 \text{and} 28.8 \mathrm{J} {\mathrm{K}}^{-1} \mathrm{mol}{ }^{-1}$ respectively.