For the combustion of 1 mol of liquid benzen | vedclass

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Question

(A) The combustion reaction of benzene is: $C_6H_{6(l)} + \frac{15}{2} O_{2(g)} \rightarrow 6 CO_{2(g)} + 3 H_2O_{(l)}$ The change in the number of ga

Vedclass · Accepted Answer

$-3264.2 \ kJ \ mol^{-1}$

Vedclass · Answer

(A) The combustion reaction of benzene is: $C_6H_{6(l)} + \frac{15}{2} O_{2(g)} ightarrow 6 CO_{2(g)} + 3 H_2O_{(l)}$ The change in the number of gaseous moles is $\Delta n_g = n_{p(g)} - n_{r(g)} = 6 - 7.5 = -1.5$. Given: $\Delta H = -3268 \ kJ \ mol^{-1}$,$T = 298 \ K$,$R = 8.314 	imes 10^{-3} \ kJ \ K^{-1} \ mol^{-1}$. The relationship between enthalpy change and internal energy change is $\Delta H = \Delta U + \Delta n_g RT$. Rearranging for internal energy change (heat of combustion at constant volume): $\Delta U = \Delta H - \Delta n_g RT$. Substituting the values: $\Delta U = -3268 - (-1.5 	imes 8.314 	imes 10^{-3} 	imes 298)$. $\Delta U = -3268 + 3.716 = -3264.284 \ kJ \ mol^{-1}$. Thus,the heat of combustion at constant volume is approximately $-3264.2 \ kJ \ mol^{-1}$.

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	$(3)$ $\Delta S = (-)$

For the combustion of $1 \ mol$ of liquid benzene at $298 \ K$,the heat of reaction at constant pressure is $-3268 \ kJ \ mol^{-1}$. What is the heat of combustion at constant volume? $(R = 8.314 \times 10^{-3} \ kJ \ K^{-1} \ mol^{-1})$

Similar Questions

At $300 \, K$ temperature,the standard heat of formation of benzoic acid $(s)$,$CO_{2(g)}$,and $H_2O_{(l)}$ are $-408$,$-393$,and $-286 \, kJ \, mol^{-1}$ respectively. At constant pressure,the heat of combustion for benzoic acid will be $..... \, kJ$.

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

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 $(3)$ $\Delta S = (-)$

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