(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

IIT 2009 All IIT

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

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At $27 \, ^oC$,one mole of an ideal gas is compressed isothermally and reversibly from a pressure of $2 \ atm$ to $10 \ atm$. The values of $\Delta E$ and $q$ are $(R = 2 \ cal \ K^{-1} \ mol^{-1})$:

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The enthalpy of sublimation of $I_{2(s)}$ is $57.3 \, kJ \, mol^{-1}$ and the enthalpy of fusion is $15.5 \, kJ \, mol^{-1}$. The enthalpy of vaporization of $I_2$ is ..................... $kJ \, mol^{-1}$. (in $.8$)

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For the reaction: $A_{(g)} + B_{(s)} \rightleftharpoons 2C_{(g)} + D_{(g)}$,given $\Delta U = 5.0 \ kcal$ and $\Delta S = 50 \ cal \ K^{-1}$ at $400 \ K$. Calculate $\Delta G$ for the reaction. (in $kcal$)

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For a hypothetical reaction $A_{2(g)} + B_{2(g)} \rightleftharpoons 2AB_{(g)}$,at $200 \ K$,$\Delta_r G$ and $\Delta_r S$ are $20 \ kJ \ mol^{-1}$ and $-20 \ J \ K^{-1} \ mol^{-1}$ respectively. If $\Delta_r C_p = 20 \ J \ K^{-1} \ mol^{-1}$,find $\Delta_r H$ at $400 \ K$ in $kJ \ mol^{-1}$.

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For a pure substance,if $T_B$ is the melting point and $T_A$ is the freezing point,which graph correctly represents the relationship between the change in entropy $(\Delta S)$ and temperature $(T)$?

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At $27 \, ^oC$,one mole of an ideal gas is compressed isothermally and reversibly from a pressure of $2 \ atm$ to $10 \ atm$. The values of $\Delta E$ and $q$ are $(R = 2 \ cal \ K^{-1} \ mol^{-1})$:

The enthalpy of sublimation of $I_{2(s)}$ is $57.3 \, kJ \, mol^{-1}$ and the enthalpy of fusion is $15.5 \, kJ \, mol^{-1}$. The enthalpy of vaporization of $I_2$ is ..................... $kJ \, mol^{-1}$. (in $.8$)

For the reaction: $A_{(g)} + B_{(s)} \rightleftharpoons 2C_{(g)} + D_{(g)}$,given $\Delta U = 5.0 \ kcal$ and $\Delta S = 50 \ cal \ K^{-1}$ at $400 \ K$. Calculate $\Delta G$ for the reaction. (in $kcal$)

For a hypothetical reaction $A_{2(g)} + B_{2(g)} \rightleftharpoons 2AB_{(g)}$,at $200 \ K$,$\Delta_r G$ and $\Delta_r S$ are $20 \ kJ \ mol^{-1}$ and $-20 \ J \ K^{-1} \ mol^{-1}$ respectively. If $\Delta_r C_p = 20 \ J \ K^{-1} \ mol^{-1}$,find $\Delta_r H$ at $400 \ K$ in $kJ \ mol^{-1}$.

For a pure substance,if $T_B$ is the melting point and $T_A$ is the freezing point,which graph correctly represents the relationship between the change in entropy $(\Delta S)$ and temperature $(T)$?

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