The heats of combustion of $CH_4, C_2H_6, C_2H_4$,and $C_2H_2$ at the same temperature are $-212.8, -373.0, -337.0$,and $-310.5 \, Kcal$ respectively. Which of these gases is the best fuel?

The heat of combustion of carbon to $CO_2$ is $-393.5 \text{ kJ/mol}$. The heat released upon formation of $35.2 \text{ g}$ of $CO_2$ from carbon and oxygen gas is

The standard molar enthalpies of formation for ethane,$CO_2$,and water $(l)$ are $-21.1$,$-94.1$,and $-68.3 \text{ kcal/mol}$ respectively. What is the standard molar enthalpy of combustion for ethane in $\text{kcal/mol}$?

When $50 \ cm^3$ of $0.2 \ N \ H_2SO_4$ is mixed with $50 \ cm^3$ of $1 \ N \ KOH$,the heat liberated is

Calculate the enthalpy change when $50 \ mL$ of $0.01 \ M$ $Ca(OH)_2$ reacts with $25 \ mL$ of $0.01 \ M$ $HCl$. Given that $\Delta H^o$ for neutralization of a strong acid and a strong base is $-13.7 \ kcal \ mol^{-1}$. (Note: The provided value in the prompt $140 \ kcal \ mol^{-1}$ is physically incorrect for neutralization; using standard value $-13.7 \ kcal \ mol^{-1}$ for calculation). (in $kcal$)

The volume of a gas decreases from $500 \ cc$ to $300 \ cc$ when a sample of gas is compressed by an average pressure of $0.6 \ atm$. During this process $10 \ J$ of heat is liberated. The change in internal energy is......$J$