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JEE Main 20265 AprilMorning Shift
Exam
JEE Main
Year
2026
Date
5 April
Shift
Morning Shift
Subject
Chemistry
Chapter
Chemical Equilibrium

JEE Main 2026 · 5 April · Morning Shift · Chemistry · Chemical Equilibrium

The values of pressure equilibrium constant recorded at different...

The values of pressure equilibrium constant recorded at different temperatures for the following equilibrium reaction have been given below
A(g)⇌B(g)+C(g)A(g) \rightleftharpoons B(g) + C(g)
1T(K−1)\dfrac{1}{T}(\text{K}^{-1})log⁡10Kp\log_{10} K_p
0.050.053.53.5
0.060.062.52.5
0.070.071.51.5

The magnitude of ΔH°R\dfrac{\Delta H°}{R} calculated from the above data is _____. (Nearest integer)

Correct answer

0

Step-by-step solution

According to the van 't Hoff equation:

log⁡10Kp=−ΔH∘2.303R(1T)+ΔS∘2.303R\log_{10} K_p = -\dfrac{\Delta H^\circ}{2.303 R} \left(\dfrac{1}{T}\right) + \dfrac{\Delta S^\circ}{2.303 R}

This represents a linear equation y=mx+cy = mx + c, where y=log⁡10Kpy = \log_{10} K_p and x=1Tx = \dfrac{1}{T}. The slope mm of the line is given by:

m=−ΔH∘2.303Rm = -\dfrac{\Delta H^\circ}{2.303 R}

From the given data table, we can calculate the slope mm using any two points, for example (0.05,3.5)(0.05, 3.5) and (0.06,2.5)(0.06, 2.5):

m=y2−y1x2−x1=2.5−3.50.06−0.05=−1.00.01=−100m = \dfrac{y_2 - y_1}{x_2 - x_1} = \dfrac{2.5 - 3.5}{0.06 - 0.05} = \dfrac{-1.0}{0.01} = -100

Equating the calculated slope to the theoretical slope:

−ΔH∘2.303R=−100-\dfrac{\Delta H^\circ}{2.303 R} = -100

ΔH∘R=100×2.303=230.3\dfrac{\Delta H^\circ}{R} = 100 \times 2.303 = 230.3

The magnitude of ΔH∘R\dfrac{\Delta H^\circ}{R} is 230.3230.3. Rounding to the nearest integer, we get 230230.

Answer: 230230
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