Thermodynamics practice · Mixed difficulty

At a constant volume the specific heat of a gas is 0.075 and its molecular weight is 40 . The gas is :

$1 \mathrm{~g}$ of benzene is burnt at $25^{\circ} \mathrm{C}$ and liberates $2.5 \mathrm{~kJ}$ heat. Heat of combustion of benzene at $25^{\circ} \mathrm{C}$ is

Given that, for the reaction,

$\frac{1}{2} \mathrm{H}_2+\frac{1}{2} \mathrm{Cl}_2 \rightarrow \mathrm{HCl}$

$\Delta H_f(\mathrm{HCl})=-93 \mathrm{~kJ} / \mathrm{mol}$

$\text { B.E }\left(\mathrm{H}_2\right)=434 \mathrm{~kJ} / \mathrm{mol}, \text { B.E }$

$\left(\mathrm{Cl}_2\right)=242 \mathrm{~kJ} / \mathrm{mol}$

The bond dissociation energy of $\mathrm{HCl}$ is

${S}+{O}_2 \rightarrow {SO}_2+x \, {kcal}$ ....(1)

${SO}_2+\frac{1}{2} {O}_2 \rightarrow {SO}_3+y \text { kcal } ...(2)$

The heat of formation of ${SO}_3$ in the above reaction is

The vapour pressure of benzene is $0.153 \times 10^5 \mathrm{Nm}^{-2}$ at $303 \mathrm{~K}$ and $0.520 \times 10^5 \mathrm{Nm}^{-2}$ at $333 \mathrm{~K}$. The mean latent heat of evaporation of benzene over this temperature range is

$\mathrm{H}_2(\mathrm{g})+\frac{1}{2} \mathrm{O}_2(\mathrm{g}) \rightarrow \mathrm{H}_2 \mathrm{O}({l})$

B.E. $(\mathrm{H}-\mathrm{H})=x_1;$ B.E. $(\mathrm{O}=\mathrm{O})=x_2;$ B.E. $(\mathrm{O}-\mathrm{H})=x_3$

Latent heat of vaporization of water liquid into water vapor $=x_4,$ then $\Delta H_{\mathrm{f}}$ (heat of formation of liquid water) is

One mole of an ideal monoatomic gas is heated in a process $P V^{5 / 2}=$ constant. By what amount heat is absorbed in the process in $26^{\circ} \mathrm{C}$ rise in temperature?

Enthalpy of $\mathrm{CH}_4+\frac{1}{2} \mathrm{O}_2 \rightarrow \mathrm{CH}_3 \mathrm{OH}$ is negative. If enthalpy of combustion of $\mathrm{CH}_4$ and $\mathrm{CH}_3 \mathrm{OH}$ are $\mathrm{x}$ and $\mathrm{y}$ respectively. Then which relation is correct?

An isothermal process is associated with:

Which of following is incorrect about reversible
process?

With what minimum pressure (in $\mathrm{kPa}$ ), a given volume of an ideal gas $\left(C_{p, m}=7 / 2 R\right)$, originally at $400 \mathrm{~K}$ and $100 \mathrm{kPa}$ pressure can be compressed irreversibly adiabatically in order to raise its temperature to $600 \mathrm{~K}$ :

The standard enthalpies of formation of $\mathrm{NH}_3(\mathrm{g}),\mathrm{CuO}(\mathrm{s})$ and $\mathrm{H}_2 \mathrm{O}({l})$ are $-46,-155$ and $-285 \mathrm{~kJ} /\mathrm{mol},$ respectively. The enthalpy change when $6.80 \mathrm{~g}$ of $\mathrm{NH}_3$ is passed over cupric oxide is

Calculate the enthalpy for the following reaction using the given bond energies $(\mathrm{kJ} / \mathrm{mol})$ :

$(\mathrm{C}-\mathrm{H}=414 ; \mathrm{H}-\mathrm{O}=463 ; \mathrm{H}-\mathrm{Cl}=431, \mathrm{C}-\mathrm{Cl}=326 ; \mathrm{C}-\mathrm{O}=335)$

$\mathrm{CH}_3-\mathrm{OH}(\mathrm{g})+\mathrm{HCl}(\mathrm{g}) \longrightarrow \mathrm{CH}_3-\mathrm{Cl}(\mathrm{g})+\mathrm{H}_2 \mathrm{O}(\mathrm{g})$

${H_2}$ (g)+Cl(g)=2HCl(g); ∆H(298 K)=22.06 kcal. For this reaction, ∆U is equal to:

A system undergoes a certain change in state by path I and the corresponding heat absorbed and work done are $10 \mathrm{~kcal}$ and $0 \text{ erg},$ respectively. For the same change in state by path II, the respective quantities are $11 \mathrm{~kcal}$ and $0.5 \, w_{\max },$ where $w_{\max }$ represents the work done if the changes were reversibly carried out. The magnitude of $w_{\max },$ is $(1 \mathrm{~cal}=4.2 \mathrm{~J})$

The vapour pressure of benzene is $1.53 \times 10^4 {Nm}^{-2}$ at $303 {~K}$ and $5.2 \times 10^4 {Nm}^{-2}$ at $333 {~K}$. Calculate the mean latent heat of evaporation of benzene over this temperature range.

Choose the reaction with negative $\Delta S$ value.

If the heat of formation of $\mathrm{NO}_2$ is '$\mathrm{x}$'
$\left[1 / 2 \mathrm{~N}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{NO}_{2}(\mathrm{g})\right]$ the heat of reaction
$\mathrm{N}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{NO}{(\mathrm{g})}$ is $\mathrm{y}$ and the heat of reaction
$2 \mathrm{NO}{(\mathrm{g})}+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{NO}_{2}(\mathrm{g})$ is $\mathrm{z}$, then

${HCl}$ (in 20 moles ${H}_2 {O}$) +20 moles of ${H}_2 {O} \longrightarrow {HCl}$ (in 40 moles of water). $\Delta {H}$ for the above process is called.

During an adiabatic process:

For the reaction $\mathrm{CO}(\mathrm{g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \longrightarrow$ $\mathrm{CO}_2(\mathrm{~g}), \Delta \mathrm{H}$ and $\Delta \mathrm{S}$ are $-{2 8 3} \mathrm{kJ}$ and $-87 \mathrm{JK}^{-1}$, respectively. It was intended to carry out this reaction at $1000,1500,3000$ and $3500 \mathrm{~K}$. At which of these temperatures would this reaction be thermodynamically spontaneous?

If a closed system has adiabatic boundaries, then
at least one boundary must be

For which of the process, ∆S is negative?

Equal volume of two monoatomic gases, A and B, at same temperature and pressure are mixed. The ratio of specific heats $(\;{C_P}/{C_V})$ of the mixture will be:

∆H for transition of carbon in the diamond form to carbon in the graphite form, is – 453.5 cal. This suggests that :

${q}=-{w}$ is not true for :

Given

(i) $\mathrm{C}+\mathrm{O}_2 \longrightarrow \mathrm{CO}_2 ; \Delta \mathrm{H}^{\circ}=-\mathrm{x} \mathrm{kJ}$

(ii) $2 \mathrm{CO}+\mathrm{O}_2 \longrightarrow 2 \mathrm{CO}_2 ; \Delta \mathrm{H}^{\circ}=-\mathrm{y} \mathrm{kJ}$

The enthalpy of formation of $\mathrm{CO}_2$ will be

Molar heat capacity of $\mathrm{CD}_2 \mathrm{O}$ (deuterated form of formaldehyde) vapour at constant pressure is vapour $14 \mathrm{~cal} / \mathrm{K}-\mathrm{mol}.$ The entropy change associated with the cooling of $3.2 \mathrm{~g}$ of $\mathrm{CD}_2 \mathrm{O}$ vapour from $1000 \mathrm{~K}$ to $900 \mathrm{~K}$ at constant pressure is (assume ideal gas behaviour for $\mathrm{CD}_2 \mathrm{O})$ [ln $0.9=-0.1]$

The enthalpy of atomisation of ${CCl}_4$ is $450 \mathrm{~kJ} / \mathrm{mol}$ and enthalpy of atomisation of ${COCl}_2$ is $600 \, \mathrm{kJ} / \mathrm{mol}$. The bond energy of ${C}={O}$ bond is

Assertion : -Entropy of system always increases for a spontaneous reaction.
Reason :- Entropy of reaction always decreases for spontaneous reaction.