Chemical Thermodynamics — JEE Main PYQs

For the reaction $\mathrm{A}(\mathrm{l})⟶2\mathrm{B}(\mathrm{g})$
$\Delta \mathrm{U}=2.1\mathrm{Kcal},\Delta \mathrm{S}=20\mathrm{cal}{\mathrm{K}}^{-1}$ at 300 K
Hence $\Delta \mathrm{G}$ in Kcal is

The standard heat of formation $\left({\Delta }_{\mathrm{f}}{\mathrm{H}}_{298}^0\right)$ of ethane (in $\mathrm{kJ}/\mathrm{mol}$ ), if the heat of combustion of ethane, hydrogen and graphite are $-1560,-393.5$ and $-286\mathrm{kJ}/\mathrm{mol}$ respectively is ___ …

The magnitude of work done by a gas that undergoes a reversible expansion along the path $ABC$ shown in the figure is ____
Pressure

At constant volume, 4 mol of an ideal gas when heated from 300 K to 500 K changes its internal energy by 5000 J . The molar heat capacity at constant volume is ____

The true statement amongst the following is:

The correct order of heat of combustion for following alkadienes is:

If enthalpy of atomisation for ${\mathrm{Br}}_2(\mathrm{A})$ is $\mathrm{x}$ $kJ/mol$ and bond enthalpy for ${\mathrm{Br}}_2$ is $\mathrm{y}$ $kJ/mol$, the relation between them:

Lattice enthalpy and enthalpy of solution of NaCl are $788\mathrm{kJ}{\mathrm{mol}}^{-1}$ and $4\mathrm{kJ}{\mathrm{mol}}^{-1}$, respectively. The hydration enthalpy of NaCl is:

For a dimerization reaction,
$2\mathrm{A}(\mathrm{g})\to {\mathrm{A}}_2(\mathrm{g})$,
at $298\mathrm{K},\Delta {\mathrm{U}}^{\ominus }=-20\mathrm{kJ}{\mathrm{mol}}^{-1},\Delta {\mathrm{S}}^{\ominus }=-30{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$, then the …

For a reaction,
$4\mathrm{M}(\mathrm{s})+{\mathrm{nO}}_2(\mathrm{g})\to 2{\mathrm{M}}_2{\mathrm{O}}_{\mathrm{n}}(\mathrm{s})$,
the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the p …

The variation of equilibrium constant with temperature is given below:
| ${\mathrm{T}}_2=100^{\circ }\mathrm{C}$ | …

For one mole of an ideal gas, which of these statements must be true?
(a) U and H each depends only on temperature
(b) Compressibility factor Z is not equal to 1
(c) ${\mathrm{C}}_{\mathrm{P},\mathrm{m}}-{\mathrm{C}}_{\mathrm{V},\mathrm{m}}=\mathrm{R}$
(d) …

Five moles of an ideal gas at 1 bar and 298 K is expanded into vacuum to double the volume. The work done is :

For silver $C_P(J{K}^{-1}{\mathrm{mol}}^{-1})=23+0.01T$. If the temperature (T) of 3 moles of silver is raised from 300 K to 1000 K at 1 atm pressure, the value of $\Delta H$ will be close to:

Which one of the following equations does not correctly represent the first law of thermodynamics for the given processes involving an ideal gas? (Assume non expansion work is zero)

5 moles of an ideal gas at 100 K are allowed to undergo reversible compression till its temperature becomes 200 K. If ${\mathrm{C}}_{\mathrm{v}}=28{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$, calculate $\Delta \mathrm{U}$ and $\Delta \mathrm{pV}$ for this process. ( …

Among the following the set of parameters that represents path functions, is:
(a) $q+w$
(b) q
(c) w
(d) H - TS

A process that has $\Delta \mathrm{H}=200\mathrm{J}{\mathrm{mol}}^{-1}$ and $\Delta \mathrm{S}=40{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$. Out of the values given below, choose the minimum temperature above which the process will be spontaneous:

The reaction:
$\mathrm{MgO}(\mathrm{s})+\mathrm{C}(\mathrm{s})\to \mathrm{Mg}(\mathrm{s})+\mathrm{CO}(\mathrm{g})$, for which ${\Delta }_{\mathrm{r}}{\mathrm{H}}^0=+491.1\mathrm{kJ}{\mathrm{mol}}^{-1}$ and …

The standard reaction Gibbs energy for a chemical reaction at an absolute temperature T is given by
${\Delta }_{\mathrm{r}}{\mathrm{G}}^0=\mathrm{A}-\mathrm{BT}$
Where $A$ and $B$ are non - zero constant. Which of the following is TRUE about this reaction?

For the equilibrium
$2{\mathrm{H}}_2\mathrm{O}\rightleftharpoons {\mathrm{H}}_3{\mathrm{O}}^{+}+{\mathrm{OH}}^{-}$, the value of $\Delta {\mathrm{G}}^0$ at 298 K is approximately:

Enthalpy of sublimation of iodine is $24\mathrm{cal}{\mathrm{g}}^{-1}$ at $200^{\circ }\mathrm{C}$. If specific heat of ${\mathrm{I}}_2(\mathrm{s})$ and ${\mathrm{I}}_2$ (vap) are 0.055 and $0.031\mathrm{cal}{\mathrm{g}}^{-1}{\mathrm{K}}^{-1}$ respectively, then enthalpy of subl …

An ideal gas is allowed to expand from 1 L to 10 L against a constant external pressure of 1bar. The work done in kJ is:

The difference between $\Delta \mathrm{H}$ and $\Delta \mathrm{U}(\Delta \mathrm{H}-\Delta \mathrm{U})$, when the combustion of one mole of heptane(I) is carried out a temperature T is equal to

Two blocks of the same metal having same mass and at temperature $T_1$ and $T_2$ respectively, are brought in contact with each other and allowed to attain thermal equilibrium at constant pressure. The change in entropy, $\Delta \mathrm{S}$, for this process is:

For the chemical reaction $\mathrm{X}\rightleftharpoons \mathrm{Y}$, the standard reaction Gibbs energy depends on temperature T (in K) as
${\Delta }_{\mathrm{r}}{\mathrm{G}}^0({\mathrm{in}\mathrm{kJ}\mathrm{mol}}^{-1})=120-\frac{3}{8}\mathrm{T}$
The major component of the reaction mixture at T …

For a disatomic ideal gas in a closed system, which of the following plots does not correctly describe the relation between various thermodynamic quantities?

The INCORRECT match in the following is:

Given :
(i) C (graphite) $+{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{CO}}_2(\mathrm{g});\Delta {\mathrm{rH}}^{\circ }=\mathrm{x}\mathrm{kJ}{\mathrm{mol}}^{-1}$
(ii) C (graphite) …

During compression of a spring the work done is 10 kJ and 2 kJ escaped to the surroundings as heat. The change in internal energy, $\Delta \mathrm{U}$ (in kJ) is:

The entropy change associated with the conversion of 1 kg of ice at 273 K to water vapours at 383 K is: (Specific heat of water liquid and water vapours are $4.2\mathrm{kJ}{\mathrm{K}}^{-1}{\mathrm{kg}}^{-1}$ and $2.0\mathrm{kJ}{\mathrm{K}}^{-1}{\mathrm{kg}}^{-1}$, heat o …

Consider the reversible isothermal expansion of an ideal gas in a closed system at two different temperatures $T_1\&T_2\left(T_1<T_2\right)$. The correct graphical depiction of the dependence of work done(w) on the final volume(v).

A process will be spontaneous at all temperatures if:

Which of the following lines correctly show the temperature dependence of equilibrium constant, K, for an exothermic reaction?

The combustion of benzene (l) gives ${\mathrm{CO}}_2(\mathrm{g})$ and ${\mathrm{H}}_2\mathrm{O}(\mathrm{l})$. Given that heat of combustion of benzene at constant volume is $-3263.9\mathrm{kJ}{\mathrm{mol}}^{-1}$ at $25^{\circ }\mathrm{C}$; heat of combustion (in …

$\Delta \mathrm{U}$ is equal to :

Given
${\mathrm{C}}_{\text{(graphite) }}+{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{CO}}_2(\mathrm{g})$;
${\Delta }_{\mathrm{r}}{\mathrm{H}}^{\circ }=-393.5\mathrm{kJ}{\mathrm{mol}}^{-1}$ …

The heats of combustion of carbon and carbon monoxide are -393.5 and $-283.5\mathrm{kJ}{\mathrm{mol}}^{-1}$, respectively. The heat of formation (in kJ ) of carbon monoxide per mole is :

The following reaction is performed at 298 K .
$2\mathrm{NO}(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons 2{\mathrm{NO}}_2(\mathrm{g})$
The standard free energy of formation of $\mathrm{NO}(\mathrm{g})$ is $86.6\mathrm{kJ}/\mathrm{mol}$ at 298 K . What is the …

For complete combustion of ethanol, ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}(\ell )+3{\mathrm{O}}_2(\mathrm{g})⟶2{\mathrm{CO}}_2(\mathrm{g})+3{\mathrm{H}}_2\mathrm{O}(\ell )$, the amount of heat produced as measured in bomb calorimeter, is …

A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of $37.0^{\circ }\mathrm{C}$. As it does so, it absorbs 208J of heat. The values of q and w for the process will be: ( …

The incorrect expression among the following is :

The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of $10{\mathrm{dm}}^3$ to a volume of $100{\mathrm{dm}}^3$ at $27^{\circ }\mathrm{C}$ is :

The standard enthalpy of formation of ${\mathrm{NH}}_3$ is $-46.0\mathrm{kJ}{\mathrm{mol}}^{-1}$. If the enthalpy of formation of ${\mathrm{H}}_2$ from its atoms is $-436\mathrm{kJ}{\mathrm{mol}}^{-1}$ and that of ${\mathrm{N}}_2$ is …

For a particular reversible reaction at temperature $\mathrm{T},\Delta \mathrm{H}$ and $\Delta \mathrm{S}$ were found to be both +ve . If ${\mathrm{T}}_{\mathrm{e}}$ is the temperature at equilibrium, the reaction would be spontaneous when

On the basis of the following thermochemical data : ( $\Delta {\mathrm{fG}}^{\circ }{\mathrm{H}}_{(\mathrm{aq})}^{+}=0$ )
${\mathrm{H}}_2\mathrm{O}(\ell )\to {\mathrm{H}}^{+}(\mathrm{aq})+{\mathrm{OH}}^{-}(\mathrm{aq});\Delta \mathrm{H}=57.32\mathrm{kJ}$ …

Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below: …

Standard entropy of $X_2,Y_2$ and $X{Y}_3$ are 60,40 and $50{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$, respectively. For the reaction, $\frac{1}{2}{X}_2+\frac{3}{2}{Y}_2\to X{Y}_3,\Delta H=-30\mathrm{kJ}$, to be at equilibrium, the temperature will be

Assuming that water vapour is an ideal gas, the internal energy ($\Delta \mathrm{U}$) when 1 mol of water is vapourised at 1 bar pressure and $100^{\circ }\mathrm{C}$, (Given: Molar enthalpy of vapourization of water at 1 bar and …

Identify the correct statement regarding a spontaneous process