Draw full reaction pathway diagrams including activation for the combustion of sulphur to form sulphur dioxide.

Identify each of the following reactions as $∆{\mathrm{H}}_{\mathrm{r}}^{°}, ∆{\mathrm{H}}_{\mathrm{f}}^{°} \mathrm{or} ∆{\mathrm{H}}_{\mathrm{c}}^{°}$,

${\mathrm{MgCO}}_3\left(\mathrm{s}\right)\to \mathrm{MgO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$.

Identify each of the following reactions as $∆{\mathrm{H}}_{\mathrm{r}}^{°}, ∆{\mathrm{H}}_{\mathrm{f}}^{°} \mathrm{or} ∆{\mathrm{H}}_{\mathrm{c}}^{°}$,

$\mathrm{C}\left(\mathrm{graphite}\right)\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{CO}}_2\left(\mathrm{g}\right)$.

Identify each of the following reactions as $∆{\mathrm{H}}_{\mathrm{r}}^{°}, ∆{\mathrm{H}}_{\mathrm{f}}^{°} \mathrm{or} ∆{\mathrm{H}}_{\mathrm{c}}^{°}$,

$\mathrm{HCl}\left(\mathrm{g}\right)+{\mathrm{NH}}_3\left(\mathrm{g}\right)\to {\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{s}\right)$.

Identify each of the following reactions as $∆{\mathrm{H}}_{\mathrm{r}}^{°}, ∆{\mathrm{H}}_{\mathrm{f}}^{°} \mathrm{or} ∆{\mathrm{H}}_{\mathrm{c}}^{°}$,

${\mathrm{H}}_2\left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2\to {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$.

A student added $10 \mathrm{g} (0.25 \mathrm{mol})$ of sodium hydroxide to $40 {\mathrm{cm}}^3$ of water to make a concentrated solution. All the sodium hydroxide dissolved. The student measured the maximum temperature rise. The student suggested that these results would give an accurate value for the standard enthalpy change of solution. Give two reasons why the student is incorrect.

A student calculated the standard enthalpy change of combustion of ethanol $∆{\mathrm{H}}_{\mathrm{c}}^{°}\left[{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\right]$ by calorimetry as $- 870 \mathrm{kJ} {\mathrm{mol}}^{-1}$. The data book value is $-1367 \mathrm{kJ} {\mathrm{mol}}^{-1}$. Explain why there is a difference between these values.