Embibe Experts Solutions for Chapter: Thermodynamics, Exercise 4: Exercise-4

The work done (in erg) for the reversible expansion of one mole of an ideal gas from a volume of $10$ Litres to $20$ Litres at $25°\mathrm{C}$ is

The enthalpy of combustion of propane $\left({\mathrm{C}}_3{\mathrm{H}}_8\right)$ gas in terms of given data is :

Bond energy $\left(\mathrm{kJ} {\mathrm{mol}}^{-1}\right)$

Resonance energy of ${\mathrm{CO}}_2$ is $-\mathrm{z} \mathrm{kJ} {\mathrm{mol}}^{-1}$ and ${\mathrm{\Delta H}}_{\text{vaporization }}\left[{\mathrm{H}}_2\mathrm{O}\left(\mathrm{\ell }\right)\right]$ is $\mathrm{y} \mathrm{kJ} {\mathrm{mol}}^{-1}$.

From given following equations and $\mathrm{\Delta H}°$ values at $298 \mathrm{K},$ determine the enthalpy of reaction (in $\mathrm{kJ}):-$

${\mathrm{C}}_2{\mathrm{H}}_4\left(\mathrm{g}\right)+6{\mathrm{F}}_2\left(\mathrm{g}\right)⟶2{\mathrm{CF}}_4\left(\mathrm{g}\right)+4\mathrm{HF}\left(\mathrm{g}\right); {\mathrm{\Delta H}}^{\mathrm{o}}=$?

${\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{F}}_2\left(\mathrm{g}\right)⟶2\mathrm{HF}\left(\mathrm{g}\right); {\mathrm{\Delta H}}_1°=-537 \mathrm{kJ}$

${\mathrm{C}}_{\left(\mathrm{s}\right)}+2{\mathrm{F}}_2\left(\mathrm{g}\right)⟶{\mathrm{CF}}_4\left(\mathrm{g}\right); {\mathrm{\Delta H}}_2°=-680 \mathrm{kJ}$

$2{\mathrm{C}}_{\left(\mathrm{s}\right)}+2{\mathrm{H}}_2\left(\mathrm{g}\right)⟶{\mathrm{C}}_2{\mathrm{H}}_4\left(\mathrm{g}\right); {\mathrm{\Delta H}}_3^0=52 \mathrm{kJ}$

The enthalpies of decomposition of methane $\left({\mathrm{CH}}_4\right)\left(\mathrm{g}\right)$ and ethane $\left({\mathrm{C}}_2{\mathrm{H}}_6\right)\left(\mathrm{g}\right)$ are $400$ and $670 \mathrm{kJmol}{-}^1$, respectively. The $\mathrm{\Delta Hc}-\mathrm{c}$ in ${\mathrm{kJmol}}^{-1}$ is

Enthalpy of vaporization of benzene is $+35.3 \mathrm{kJ} {\mathrm{mol}}^{-1}$ at its boiling point, ${80}^{\circ }\mathrm{C}$. The entropy change in the transition of the vapour to liquid at its boiling point [ in ${\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$] is .....

The value of $\Delta {\mathrm{H}}_{\text{transition }}$ of $\mathrm{C}$ (graphite) $⟶\mathrm{C}$ (diamond) is $1.9 \mathrm{kJ}/\mathrm{mol}$ at $25 °\mathrm{C}$ entropy of graphite is higher than entropy of diamond. This implies that:

For the reaction $2{\mathrm{Ag}}_2\mathrm{O} \left(\mathrm{s}\right)⟶4\mathrm{Ag} \left(\mathrm{s}\right)+{\mathrm{O}}_2 \left(\mathrm{g}\right), \mathrm{\Delta H}$ is $61.17 \mathrm{kJ} {\mathrm{mol}}^{-1}$ and $\Delta \mathrm{S}$ is $132 \mathrm{J} {\mathrm{K}}^{-1 }{\mathrm{mol}}^{-1}.$
Compute the temperature above, which the given reaction will be spontaneous.

Select the correct molar entropy at corresponding temperature using following data:
(i) Heat capacity of solid from $0 \mathrm{K}$ to normal melting point $200 \mathrm{K}$
$\begin{array}{cc}{\mathrm{C}}_{\mathrm{P},\mathrm{m}} \left(\mathrm{s}\right)=0.035 \mathrm{T}& \mathrm{J} {\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}\end{array}$
(ii) Enthalpy of fusion$=7.5 \mathrm{KJ} {\mathrm{mol}}^{-1}.$
(iii) Enthalpy of vaporisation$=30 \mathrm{KJ} {\mathrm{mol}}^{-1}.$
(iv) Heat capacity of liquid form $200 \mathrm{K}$ to normal boiling point $300 \mathrm{K}$
${\mathrm{C}}_{\mathrm{P},\mathrm{m}} \left(\mathrm{\ell }\right)=60+0.016 \mathrm{T} \mathrm{J} {\mathrm{K}}^{-1} {\mathrm{mol}}^{-1}$
(v) Heat capacity of gas from $300 \mathrm{K}$ to $600 \mathrm{K}$ at $1$ atm
$\begin{array}{cc}{\mathrm{C}}_{\mathrm{P},\mathrm{m}} \left(\mathrm{g}\right)=50.0& \mathrm{J} {\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}\end{array}$