(A) The heat released during combustion is absorbed by the calorimeter: $q = C_V \times \Delta T$.Given $C_V = 2.5 \ kJ \ K^{-1}$ and $\Delta T = 298.

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(A) The heat released during combustion is absorbed by the calorimeter: $q = C_V \times \Delta T$.Given $C_V = 2.5 \ kJ \ K^{-1}$ and $\Delta T = 298.45 \ K - 298.0 \ K = 0.45 \ K$.Heat released for $3.5 \ g$ of gas $= 2.5 \ kJ \ K^{-1} \times 0.45 \ K = 1.125 \ kJ$.Moles of gas $= \frac{\text{mass}}{\text{molecular weight}} = \frac{3.5 \ g}{28 \ g \ mol^{-1}} = 0.125 \ mol$.Enthalpy of combustion per mole $= \frac{\text{Heat released}}{\text{moles}} = \frac{1.125 \ kJ}{0.125 \ mol} = 9 \ kJ \ mol^{-1}$.

Class 11 Chemistry Thermodynamics Mix Examples-Thermodynamics and Thermochemistry

In a constant volume calorimeter,$3.5 \ g$ of a gas with molecular weight $28$ was burnt in excess oxygen at $298.0 \ K$. The temperature of the calorimeter was found to increase from $298.0 \ K$ to $298.45 \ K$ due to the combustion process. Given that the heat capacity of the calorimeter is $2.5 \ kJ \ K^{-1}$,the numerical value for the enthalpy of combustion of the gas in $kJ \ mol^{-1}$ is

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$9$
B
$4$
C
$5$
D
$6$

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For a diatomic ideal gas in a closed system,which of the following plots does not correctly describe the relation between various thermodynamic quantities?

DifficultJEE MAIN 2019

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$A$ gas at $10 \, atm$ pressure and $300 \, K$ temperature undergoes adiabatic reversible expansion to $5 \, atm$ pressure and $290 \, K$ temperature. The molar heat capacity $C_v$ of the gas in $cal \, mol^{-1} \, K^{-1}$ is:

Medium

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Consider the following statements:
Statement-$I$: During isothermal expansion of an ideal gas,its enthalpy decreases.
Statement-$II$: When $2.0 \ L$ of an ideal gas expands isothermally into vacuum,$\Delta U = 0$.

MediumAP EAMCET 2025

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The enthalpies of combustion of cyclohexane $(C_6H_{12})$, cyclohexene $(C_6H_{10})$ and $H_2$ are $-3920 \text{ kJ mol}^{-1}$, $-3800 \text{ kJ mol}^{-1}$ and $-241 \text{ kJ mol}^{-1}$ respectively. The enthalpy of hydrogenation of cyclohexene is

DifficultMHT CET 2026

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Molar enthalpy change for vapourisation of $1.0 \ mol$ of water at $1.0 \ bar$ and $100 ^{\circ} C$ is $41.0 \ kJ \ mol^{-1}$. If water vapour is assumed to be an ideal gas,the internal energy change for $1.0 \ g$ of water in $kJ$ is

MediumAP EAMCET 2017

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For a diatomic ideal gas in a closed system,which of the following plots does not correctly describe the relation between various thermodynamic quantities?

$A$ gas at $10 \, atm$ pressure and $300 \, K$ temperature undergoes adiabatic reversible expansion to $5 \, atm$ pressure and $290 \, K$ temperature. The molar heat capacity $C_v$ of the gas in $cal \, mol^{-1} \, K^{-1}$ is:

Consider the following statements:Statement-$I$: During isothermal expansion of an ideal gas,its enthalpy decreases.Statement-$II$: When $2.0 \ L$ of an ideal gas expands isothermally into vacuum,$\Delta U = 0$.

The enthalpies of combustion of cyclohexane $(C_6H_{12})$, cyclohexene $(C_6H_{10})$ and $H_2$ are $-3920 \text{ kJ mol}^{-1}$, $-3800 \text{ kJ mol}^{-1}$ and $-241 \text{ kJ mol}^{-1}$ respectively. The enthalpy of hydrogenation of cyclohexene is

Molar enthalpy change for vapourisation of $1.0 \ mol$ of water at $1.0 \ bar$ and $100 ^{\circ} C$ is $41.0 \ kJ \ mol^{-1}$. If water vapour is assumed to be an ideal gas,the internal energy change for $1.0 \ g$ of water in $kJ$ is

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Consider the following statements:
Statement-$I$: During isothermal expansion of an ideal gas,its enthalpy decreases.
Statement-$II$: When $2.0 \ L$ of an ideal gas expands isothermally into vacuum,$\Delta U = 0$.