Calculate the heat of formation of $PCl_{5(s)}$ from the following data:
$2P_{(s)} + 3Cl_{2(g)} \to 2PCl_{3(l)}; \Delta H_1 = -151.8 \ kcal$
$PCl_{3(l)} + Cl_{2(g)} \to PCl_{5(s)}; \Delta H_2 = -32.8 \ kcal$
Determine the enthalpy of formation for $PCl_{5(s)}$ in $kcal$.

The heat of neutralization of a strong acid by a strong base is nearly equal to

When $600 \; mL$ of $0.2 \; M \; HNO_3$ is mixed with $400 \; mL$ of $0.1 \; M \; NaOH$ solution in a flask,the rise in temperature of the flask is $\dots \times 10^{-2} \; ^{\circ}C$. (Enthalpy of neutralisation $= 57 \; kJ \; mol^{-1}$ and Specific heat of water $= 4.2 \; J \; K^{-1} \; g^{-1}$) (Neglect heat capacity of flask)

When ethyne is passed through a red hot tube,the formation of benzene takes place :-
$\Delta H_{f(C_2H_2)(g)}^o = 230 \ kJ \ mol^{-1}$
$\Delta H_{f(C_6H_6)(g)}^o = 85 \ kJ \ mol^{-1}$
Calculate the standard heat of trimerisation of ethyne to benzene.
$3C_2H_{2(g)} \to C_6H_{6(g)}$
......$kJ \ mol^{-1}$

The heat evolved per mole of $H^+$ ions during the neutralization of a strong acid and a strong base is ......

What is the enthalpy change for the reaction $2C(\text{graphite}) + 3H_{2(g)} \rightarrow C_2H_{6(g)}$ called?