Thermodynamics Questions | JEE Main Chemistry Chapter Wise Question Papers

Q 1 :
Which of the following is not correct? [2024]

$∆ G$ is zero for a reversible reaction.
$∆ G$ is negative for a spontaneous reaction.
$∆ G$ is positive for a spontaneous reaction.
$∆ G$ is positive for a non-spontaneous reaction.

1

2

3

4

(C) $∆ G = 0 \Rightarrow$ reaction at equilibrium

$∆ G > 0 \Rightarrow$ non spontaneous reaction

$∆ G < 0 \Rightarrow$ spontaneous reaction

Q 2 :
Consider the following reaction at 298 K. $\frac{3}{2} O_{2 (g)} ⇌ O_{3 (g)}$ . $K_{p} = 2.47 \times 10^{- 29}, Δ_{r} G^{Θ}$ for the reaction is __________ kJ.

(Given R $= 8.314$ ${JK}^{- 1}$ ${mol}^{- 1}$ ) [2024]

0%

(163)

$\log (K) = \log_{10} (2.47 \times 10^{- 29}) \approx \log_{10} (25 \times 10^{- 30})$

$= \log_{10} (5^{2} \times 10^{- 30}) = 2 \log_{10} 5 - 30$ $\log$ $10$

$= 2 \times 0.7 - 30 \times 1 = - 28.6$

$Δ G ° = - 2.303$ $RT$ $\log_{10} K$

$Δ G ° = - 2.303 \times 8.314 \frac{J}{K mol} \times 298 K \times \log_{10} (2.47 \times 10^{- 29})$

$= - 2.303 \times 8.314 \times 298 \times (- 28.6) J m o l^{- 1} = 163.2 k J m o l^{- 1}$

Q 3 :
For the reaction at 298 K, 2A + B $\to$ C. $∆ H$ = 400 kJ ${mol}^{- 1}$ and $∆ S$ = 0.2 kJ ${mol}^{- 1}$ $K^{- 1}$ . The reaction will become spontaneous above ________ K. [2024]

0%

(2000)

For reaction to be spontaneous,

$Δ G < 0$

$Δ H - T Δ S < 0$

$400 kJ$ ${mol}^{- 1} - T \times 0.2 kJ$ ${mol}^{- 1} K^{- 1} < 0$

$400 kJ$ ${mol}^{- 1} < T \times 0.2 kJ$ ${mol}^{- 1} K^{- 1}$

$T > \frac{400}{0.2} K$

$T > 2000 K$

Q 4 :
When $Δ H_{vap} = 30 kJ / mol$ and $∆ S_{vap} = 75 J$ $m o l^{- 1}$ $K^{- 1}$ , then the temperature of vapour, at one atmosphere is ___________ K. [2024]

0%

(400)

When external pressure is 1 atm ,then vapours are formed at normal boiling point of the liquid. So in the question, normal boiling point of the liquid is asked.

$Δ S_{vap} = \frac{Δ H_{vap}}{T_{bpt}}$

$75 J$ $m o l^{- 1} K^{- 1} = \frac{30 \times 1000 J m o l^{- 1}}{T_{b p t}}$

$T_{bpt} = 400 K$

Topic Question Set

Q 1 :
Which of the following is not correct? [2024]

Q 2 :
Consider the following reaction at 298 K. $\frac{3}{2} O_{2 (g)} ⇌ O_{3 (g)}$ . $K_{p} = 2.47 \times 10^{- 29}, Δ_{r} G^{Θ}$ for the reaction is __________ kJ.

(Given R $= 8.314$ ${JK}^{- 1}$ ${mol}^{- 1}$ ) [2024]

0%

Q 3 :
For the reaction at 298 K, 2A + B $\to$ C. $∆ H$ = 400 kJ ${mol}^{- 1}$ and $∆ S$ = 0.2 kJ ${mol}^{- 1}$ $K^{- 1}$ . The reaction will become spontaneous above ________ K. [2024]

0%

Q 4 :
When $Δ H_{vap} = 30 kJ / mol$ and $∆ S_{vap} = 75 J$ $m o l^{- 1}$ $K^{- 1}$ , then the temperature of vapour, at one atmosphere is ___________ K. [2024]

0%

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Topic Question Set

Q 1 : Which of the following is not correct? [2024]

Q 2 : Consider the following reaction at 298 K. 32O2(g)⇌O3(g). Kp=2.47×10-29,ΔrGΘ for the reaction is __________ kJ. (Given R=8.314 JK-1 mol-1) [2024]

0%

Q 3 : For the reaction at 298 K, 2A + B→C. ∆H = 400 kJ mol-1 and ∆S = 0.2 kJ mol-1 K-1. The reaction will become spontaneous above ________ K. [2024]

0%

Q 4 : When ΔHvap=30kJ/mol and ∆Svap=75J mol-1 K-1, then the temperature of vapour, at one atmosphere is ___________ K. [2024]

0%

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Q 1 :
Which of the following is not correct? [2024]

Q 2 :
Consider the following reaction at 298 K. $\frac{3}{2} O_{2 (g)} ⇌ O_{3 (g)}$ . $K_{p} = 2.47 \times 10^{- 29}, Δ_{r} G^{Θ}$ for the reaction is __________ kJ.

(Given R $= 8.314$ ${JK}^{- 1}$ ${mol}^{- 1}$ ) [2024]

Q 3 :
For the reaction at 298 K, 2A + B $\to$ C. $∆ H$ = 400 kJ ${mol}^{- 1}$ and $∆ S$ = 0.2 kJ ${mol}^{- 1}$ $K^{- 1}$ . The reaction will become spontaneous above ________ K. [2024]

Q 4 :
When $Δ H_{vap} = 30 kJ / mol$ and $∆ S_{vap} = 75 J$ $m o l^{- 1}$ $K^{- 1}$ , then the temperature of vapour, at one atmosphere is ___________ K. [2024]