Chemical Thermodynamics — JEE Main PYQs

The enthalpy change for the conversion of $\frac{1}{2}{\mathrm{Cl}}_2(\mathrm{g})$ to ${\mathrm{Cl}}^{-}(\mathrm{aq})$ is $(-)$ ______ $\mathrm{kJ}{\mathrm{mol}}^{-1}$ (Nearest integer)

Given: …

$\mathrm{C}(\mathrm{s})+{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{CO}}_2(\mathrm{g})+400\mathrm{kJ}$
$\mathrm{C}(\mathrm{s})+\frac{1}{2}{\mathrm{O}}_2(\mathrm{g})\to \mathrm{CO}(\mathrm{g})+100\mathrm{kJ}$
When coal of purity $60\%$ is allowed to bu …

Which of the following relation is not correct?

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R

Assertion A : The reduction of a metal oxide is easier if the metal formed is in liquid state than solid state.

Reason R : The value of $\Delta {\mathrm{G}}^{\Theta }$ becomes mor …

Among the following the number of state variable is ____.
Internal energy (U)
Volume (V)
Heat (q)
Enthalpy (H)

The molar heat capacity for an ideal gas at constant pressure is $20.785\mathrm{J}{\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}$. The change in internal energy is 5000 J upon heating it from 300 K to 500 K . The number of moles of the gas at constant volume is $\_\_\_\_$ [Nearest intege …

The enthalpy of combustion of propane, graphite and dihydrogen at 298 K are: -2220.0 kJ mol⁻¹, -393.5 kJ mol⁻¹ and -285.8 kJ mol⁻¹ respectively. The magnitude enthalpy of formation of propane (C₃H₈) is........ kJ mol⁻¹. (Nearest integer)

For the reaction
${\mathrm{H}}_2{\mathrm{F}}_2(\mathrm{g})\to {\mathrm{H}}_2(\mathrm{g})+{\mathrm{F}}_2(\mathrm{g})$
$\Delta \mathrm{U}=-59.6\mathrm{kJ}{\mathrm{mol}}^{-1}$ at $27^{\circ }\mathrm{C}$.
The enthalpy change for the above reaction is (-)
____ …

A gas (Molar mass $=280\mathrm{g}{\mathrm{mol}}^{-1}$) was burnt in excess ${\mathrm{O}}_2$ in a constant volume calorimeter and during combustion the temperature of calorimeter increased from 298.0 K to 298.45 K. If the heat capacity of calorimeter is …

While performing a thermodynamics experiment, a student made the following observations, $\mathrm{HCl}+\mathrm{NaOH}\to \mathrm{NaCl}+\mathrm{H}{}_2\mathrm{O}$ $\Delta \mathrm{H}=-57.3\mathrm{kJ}{\mathrm{mol}}^{-1}$ $\mathrm{CH}{}_3\mathrm{COOH}+\mathrm{NaOH}\to \mathrm{CH}{}_3\mathrm{COONa}+\mathrm{H}{}_2\mathrm{O}$ $\Delta \mathrm{H}=-55.3\mathrm{kJ}{\mathrm{mol}}^{-1}$.

T …

$2.4\mathrm{g}$ coal is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atm pressure.

The temperature of the calorimeter rises from 298 K to 300 K . The enthalpy change during the combustion of coal is $-\mathrm{x}\mathrm{kJ}{\mathrm{mol}}^{-1}$. The value of x …

For combustion of one mole of magnesium in an open container at 300 K and 1 bar pressure, ${\Delta }_{\mathrm{C}}{\mathrm{H}}^{\ominus }=-601.70\mathrm{kJ}{\mathrm{mol}}^{-1}$, the magnitude of change in internal energy for the reaction is ______ kJ. (Nearest integer)
(Given : …

When 5 moles of He gas expand isothermally and reversibly at 300 K from 10 litre to 20 litre, the magnitude of the maximum work obtained is ____ J. [nearest integer]
(Given: $\mathrm{R}=8.3\mathrm{J}{\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}$ and $\log 2=0.3010$)

4.0 L of an ideal gas is allowed to expand isothermally into vacuum until the total volume is 20 L. The amount of heat absorbed in this expansion is ______ L atm.

2.2 g of nitrous oxide $\left({\mathrm{N}}_2\mathrm{O}\right)$ gas is cooled at a constant pressure of 1 atm from 310 K to 270 K causing the compression of the gas from 217.1 mL to 167.75 mL . The change in internal energy of the process, $\Delta \mathrm{U}$ is ' -x ' J . The va …

A fish swimming in water body when taken out from the water body is covered with a film of water of weight 36 g. When it is subjected to cooking at $100^{\circ }\mathrm{C}$, then the internal energy for vaporization in $\mathrm{kJ}{\mathrm{mol}}^{-1}$ is ______. [nearest integ …

$40\%$ of HI undergoes decomposition to ${\mathrm{H}}_2$ and ${\mathrm{I}}_2$ at $300\mathrm{K}$. $\Delta {\mathrm{G}}^{\ominus }$ for this decomposition reaction at one atmosphere pressure is $\_\_\_\_$ $\mathrm{J}{\mathrm{mol}}^{-1}$. [nearest integer]
(Use …

For complete combustion of methanol
${\mathrm{CH}}_3\mathrm{OH}(\mathrm{l})+\frac{3}{2}{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{CO}}_2(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{l})$
the amount of heat produced as measured by bomb calorimeter is …

Match List-I with List-II

List-I:
(A) Spontaneous process
(B) Process with $\Delta \mathrm{P}=0$, $\Delta \mathrm{T}=0$
(C) $\Delta {\mathrm{H}}_{\text{reaction}}$
(D) Exothermic process

List-II:
(I) $\Delta \mathrm{H}<0$
(II) $\Delta {\mathrm{G}}_{\mathrm{T},\mathrm{P}}<0$
(III) …

When 600 mL of $0.2\mathrm{M}{\mathrm{HNO}}_3$ is mixed with 400 mL of 0.1 M NaOH solution in a flask, the rise in temperature of the flask is ______ $\times 10^{-2}$ ${}^0\mathrm{C}$.
(Enthalpy of neutralisation $=57\mathrm{kJ}{mo1}^{-1}$ and Specific heat of water …

2O₃(g) ⇌ 3O₂(g)

At 300 K, ozone is fifty percent dissociated. The standard free energy change at this temperature and 1 atm pressure is (-) ______ J mol⁻¹ (Nearest integer)
[Given: ln 1.35 = 0.3 and R = 8.3 J K⁻¹ mol⁻¹]

At $25^{\circ }\mathrm{C}$ and 1 atm pressure, the enthalpies of combustion are as given below:
| …

At $25^{\circ }\mathrm{C}$ and 1 atm pressure, the enthalpy of combustion of benzene (l) and acetylene (g) are $-3268\mathrm{kJ}{\mathrm{mol}}^{-1}$ and $-1300\mathrm{kJ}{\mathrm{mol}}^{-1}$, respectively. The change in enthalpy for the reaction …

The standard entropy change for the reaction $4\mathrm{Fe}(\mathrm{s})+3{\mathrm{O}}_2(\mathrm{g})\to 2{\mathrm{Fe}}_2{\mathrm{O}}_3(\mathrm{s})$ is $-550{\mathrm{JK}}^{-1}$ at 298 K .
[Given : The standard enthalpy change for the reaction is …

The standard free energy change ( $\Delta {\mathrm{G}}^{\circ }$ ) for $50\%$ dissociation of ${\mathrm{N}}_2{\mathrm{O}}_4$ into ${\mathrm{NO}}_2$ at $27^{\circ }\mathrm{C}$ and 1 atm pressure is $-\mathrm{xJ}{\mathrm{mol}}^{-1}$. The value of x is …

For the reaction ${\mathrm{A}}_{(\mathrm{g})}\to {\mathrm{B}}_{(\mathrm{g})}$, the value of the equilibrium constant at 300 K and 1 atm is equal to 100.0. The value of ${\Delta }_{\mathrm{r}}\mathrm{G}$ for the reaction at 300 K and 1 atm in $\mathrm{J}{\mathrm{mol}}^{-1}$ …

The Born-Haber cycle for KCl is evaluated with the following data:
${\Delta }_{\mathrm{f}}{\mathrm{H}}^{\Theta }$ for $\mathrm{KCl}=-436.7{\mathrm{kJmol}}^{-1}$ ; ${\Delta }_{\text{sub }}{\mathrm{H}}^{\Theta }$ for $\mathrm{K}=89.2{\mathrm{kJmol}}^{-1}$; …

For water ${\Delta }_{\text{vap}}\mathrm{H}=41\mathrm{kJ}{\mathrm{mol}}^{-1}$ at 373 K and 1 bar pressure. Assuming that water vapour is an ideal gas that occupies a much larger volume than liquid water, the internal energy change during evaporation of water is $\_\_\_\_$ …

An average person needs abut 10000 KJ energy per day. The amount of glucose (molar mass $=180.0\mathrm{g}{\mathrm{mol}}^{-1}$) needed to meet this energy requirement is ____ g,
(Nearest integer)
(Use: ${\Delta }_{\mathrm{c}}\mathrm{H}$ (glucose) …

Assuming ideal behaviour, the magnitude of $\log \mathrm{K}$ for the following reaction at $25^{\circ }\mathrm{C}$ is $x\times 10^{-1}$. The value of $x$ is $\_\_\_\_$ (integer answer) …

For a given chemical reaction $\mathrm{A}\to \mathrm{B}$ at 300 K the free energy change is $-49.4\mathrm{kJ}{\mathrm{mol}}^{-1}$ and the enthalpy of reaction is $51.4\mathrm{kJ}{\mathrm{mol}}^{-1}$. The entropy change of the reaction is ______ …

Data given for the following reaction is as follows:


| Substance | …

The reaction of cyanamide, ${\mathrm{NH}}_2{\mathrm{CN}}_{(\mathrm{s})}$ with oxygen was run in a bomb calorimeter and $\Delta U$ was found to be $-742.24\mathrm{kJ}{\mathrm{mol}}^{-1}$. The magnitude of $\Delta {\mathrm{H}}_{298}$ for the reaction …

The ionization enthalpy of ${\mathrm{Na}}^{+}$ formation from ${\mathrm{Na}}_{(\mathrm{g})}$ is $495.8\mathrm{kJ}{\mathrm{mol}}^{-1}$, while the electron gain enthalpy of Br is $-325.0\mathrm{kJ}{\mathrm{mol}}^{-1}$. Given the lattice enthalpy of NaBr is …

If the standard molar enthalpy change for combustion of graphite powder is $-2.48\times 10^2\mathrm{kJ}{\mathrm{mol}}^{-1}$, the amount of heat generated on combustion of 1 g of graphite powder is _____ kJ. (Nearest integer)

For a chemical reaction $\mathrm{A}+\mathrm{B}\rightleftharpoons \mathrm{C}+\mathrm{D}$
$\left({\Delta }_{\mathrm{r}}{\mathrm{H}}^{\ominus }=80\mathrm{kJ}{\mathrm{mol}}^{-1}\right)$ the entropy change ${\Delta }_{\mathrm{r}}{\mathrm{S}}^{\ominus }$ depends on the temperature T (in K) as …

200 mL of 0.2 M HCl is mixed with 300 mL of 0.1 M NaOH. The molar heat of neutralization of this reaction is -57.1 kJ. The increase in temperature in ${}^{\circ }\mathrm{C}$ of the system on mixing is $x\times 10^{-2}$. The value of $x$ is ______. (Nearest integer)
[Given : Specifi …

The average S-F bond energy in kJ mol⁻¹ of SF₆ is ______ (Rounded off to the nearest integer) [Given : The values of standard enthalpy of formation of SF₆(g), S(g) and F(g) are -1100, 275 and 80 kJ mol⁻¹ respectively.]

The incorrect expression among the following is:

According to the following figure, the magnitude of the enthalpy change of the reaction
$\mathrm{A}+\mathrm{B}\to \mathrm{M}+\mathrm{N}$ in kJ mol${}^{-1}$
is equal to ____ . (Integer answer)

For water at $100^{\circ }$C and 1 bar
${\Delta }_{\text{vap}}H-{\Delta }_{\text{vap}}U=$ ______ $\times 10^2$ J mol${}^{-1}$
(Round off to the Nearest integer)
[Use: R = 8.31 J mol${}^{-1}$ K${}^{-1}$]
[Assume volume of $\mathrm{H}{}_2\mathrm{O}$(l) is much smaller than volume of $\mathrm{H}{}_2\mathrm{O}$(g). Assume …

The standard enthalpies of formation of ${\mathrm{Al}}_2{\mathrm{O}}_3$ and CaO are $-1675{\mathrm{kJ}\mathrm{mol}}^{-1}$ and $-635{\mathrm{kJ}\mathrm{mol}}^{-1}$ respectively.
For the reaction
$3\mathrm{CaO}+2\mathrm{Al}\to 3\mathrm{Ca}+{\mathrm{Al}}_2{\mathrm{O}}_3$ the standard reactio …

At 298 K , the enthalpy of fusion of a solid $(\mathrm{X})$ is $2.8\mathrm{kJ}{\mathrm{mol}}^{-1}$ and the enthalpy of vaporization of the liquid $(X)$ is $98.2\mathrm{kJ}{\mathrm{mol}}^{-1}$. The enthalpy of sublimation of the substance $(X)$ in …

When 400 mL of $0.2\mathrm{M}{\mathrm{H}}_2{\mathrm{SO}}_4$ solution is mixed with 600 mL of of 0.1 M NaOH solution the increase in temperature of the final solution is ____ $\times 10^{-2}\mathrm{K}$.
(Round off to the Nearest Integer).
[Use: …

For the reaction $2{\mathrm{NO}}_2(\mathrm{g})\rightleftharpoons {\mathrm{N}}_2{\mathrm{O}}_4(\mathrm{g})$, when $\Delta \mathrm{S}=-176.0{\mathrm{JK}}^{-1}$ and $\Delta \mathrm{H}=-57.8\mathrm{kJ}{\mathrm{mol}}^{-1}$, the magnitude of $\Delta \mathrm{G}$ at 298 K for the re …

At $25^{\circ }\mathrm{C},50\mathrm{g}$ of iron reacts with HCl to form ${\mathrm{FeCl}}_2$. The evolved hydrogen gas expands against a constant pressure of 1 bar. The work done by the gas during this expansion is _____ J. (Round off to the nearest integer).
[Given: …

The gas phase reaction
$2\mathrm{A}(\mathrm{g})\rightleftharpoons {\mathrm{A}}_2(\mathrm{g})$
At 400 K has $\Delta {\mathrm{G}}^{\circ }=+25.2\mathrm{kJ}{\mathrm{mol}}^{-1}$.
The equilibrium constant ${\mathrm{K}}_{\mathrm{C}}$ for this reaction is ______ $\times 10^{-2}$.
(Rou …

During which of the following processes, does entropy decrease?
(A) Freezing of water to ice at $0^{\circ }\mathrm{C}$
(B) Freezing of water to ice at $-10^{\circ }\mathrm{C}$
(C) …

For the reaction ${\mathrm{C}}_2{\mathrm{H}}_6\to {\mathrm{C}}_2{\mathrm{H}}_4+{\mathrm{H}}_2$ the reaction enthalpy ${\Delta }_{\mathrm{r}}\mathrm{H}=$ ______ $\mathrm{kJ}{\mathrm{mol}}^{-1}$.
(Round off to the nearest integer).
[Given: Bond enthalpies in …

A system does 200 J of work and at the same time absorbs 150 J of heat. The magnitude of the change in internal energy is ______ J. (Nearest integer)