(B) For a combustion reaction,the enthalpy change $\Delta H$ is negative (exothermic).The change in the number of moles of gas is $\Delta n_g = (16 +

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(B) For a combustion reaction,the enthalpy change $\Delta H$ is negative (exothermic).The change in the number of moles of gas is $\Delta n_g = (16 + 18) - (2 + 25) = 34 - 27 = +7$.Since $\Delta n_g > 0$,the entropy change $\Delta S$ is positive $(+ve)$.As the reaction is spontaneous in an automobile engine,the Gibbs free energy change $\Delta G$ is negative $(-ve)$.

Class 11 Chemistry Thermodynamics Mix Examples-Thermodynamics and Thermochemistry

Medium

The following reaction occurs in an automobile: $2C_8H_{18(g)} + 25O_{2(g)} \to 16CO_{2(g)} + 18H_2O_{(g)}$. The signs of $\Delta H$,$\Delta S$,and $\Delta G$ would be:

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A
$+, -, +$
B
$-, +, -$
C
$-, +, +$
D
$+, +, -$

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Thermodynamics

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Mix Examples-Thermodynamics and Thermochemistry

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AIIMS 2015 Paper All AIIMS years →

In an adiabatic process,the work involved during expansion or compression of an ideal gas is given by

Medium

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Match the following processes with their corresponding entropy changes:

Process Entropy Change

$(a)$ Liquid to vapor conversion $(1)$ $\Delta S = 0$

$(b)$ Process not spontaneous at any temperature $(2)$ $\Delta S = (+)$

$(c)$ Reversible expansion of an ideal gas $(3)$ $\Delta S = (-)$

Medium

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$10 \ g$ each of $NH_3, N_2, Cl_2$ and $H_2S$ are expanded isothermally and reversibly at the same temperature. Identify the gas that performs maximum work.

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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

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For the reaction,$2Cl_{(g)} \to Cl_{2(g)}$,the signs of $\Delta H$ and $\Delta S$ respectively,are:

EasyAIIMS 2010

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Process	Entropy Change
$(a)$ Liquid to vapor conversion	$(1)$ $\Delta S = 0$
$(b)$ Process not spontaneous at any temperature	$(2)$ $\Delta S = (+)$
$(c)$ Reversible expansion of an ideal gas	$(3)$ $\Delta S = (-)$

The following reaction occurs in an automobile: $2C_8H_{18(g)} + 25O_{2(g)} \to 16CO_{2(g)} + 18H_2O_{(g)}$. The signs of $\Delta H$,$\Delta S$,and $\Delta G$ would be:

Similar Questions

In an adiabatic process,the work involved during expansion or compression of an ideal gas is given by

Match the following processes with their corresponding entropy changes: Process Entropy Change $(a)$ Liquid to vapor conversion $(1)$ $\Delta S = 0$ $(b)$ Process not spontaneous at any temperature $(2)$ $\Delta S = (+)$ $(c)$ Reversible expansion of an ideal gas $(3)$ $\Delta S = (-)$

$10 \ g$ each of $NH_3, N_2, Cl_2$ and $H_2S$ are expanded isothermally and reversibly at the same temperature. Identify the gas that performs maximum work.

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

For the reaction,$2Cl_{(g)} \to Cl_{2(g)}$,the signs of $\Delta H$ and $\Delta S$ respectively,are:

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Match the following processes with their corresponding entropy changes:

Process Entropy Change

$(a)$ Liquid to vapor conversion $(1)$ $\Delta S = 0$

$(b)$ Process not spontaneous at any temperature $(2)$ $\Delta S = (+)$

$(c)$ Reversible expansion of an ideal gas $(3)$ $\Delta S = (-)$