Calculate the vapour pressure of water at 27-C- when the aqueous tension at 77-C is 314-1 torr- Given- Heat of vapourisation of water is nearly 40 kJ-mol -e-2-3- 0-1-

Name: JEE - Grade 12 - Chemistry - Solutions - Session 04 - W04
Uploaded: 2022-07-04T10:36:42+05:30
Description: Given, nbsp; Temperature, T_1 = 77^∘C = 350 K Temperature, T_2 = 27^∘C = 300 K Aqueous tension is the vapour pressure of water, thus Vapour pressure at 350 ...

Given, nbsp; Temperature, T_1 = 77^∘C = 350 K Temperature, T_2 = 27^∘C = 300 K Aqueous tension is the vapour pressure of water, thus Vapour pressure at 350 ...

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Standard XII

Chemistry

Solids in Liquids

Calculate the...

Question

Calculate the vapour pressure of water at $27^{\circ} C$ , when the aqueous tension at $77^{\circ} C$ is $314.1 t o r r$ . (Given: Heat of vapourisation of water is nearly $40 k J / m o l$ ) [ $e^{- 2.3} = 0.1$ ]

31.4 t o r r

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62.8 t o r r

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94.2 t o r r

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15.7 t o r r

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Solution

The correct option is A $31.4 t o r r$
Given,
$Temperature, T_{1} = 77^{\circ} C = 350 K$
$Temperature, T_{2} = 27^{\circ} C = 300 K$
Aqueous tension is the vapour pressure of water, thus
$Vapour pressure at 350 K, P_{1} = 314.1 t o r r$
$Molar heat of vaporisation of water, Δ H = 40 k J / m o l$

Effect of temperature on the vapour pressure of a liquid is given by Clausius – Clapeyron equation,
$l n (\frac{P_{2}}{P_{1}}) = \frac{Δ H}{R} (\frac{1}{T_{1}} - \frac{1}{T_{2}})$
Substituting the given values, we get,
$l n (\frac{P_{2}}{314.1}) = (\frac{40000}{8.314}) (\frac{1}{350} - \frac{1}{300})$

$l n (\frac{P_{2}}{314.1}) = (4811.2) \times (\frac{- 1}{2100}) l n (\frac{P_{2}}{314.1}) = - 2.29 \frac{P_{2}}{314.1} = 0.1 P_{2} = 31.4 t o r r$
$Vapour pressure of water at 57^{\circ} C, P_{2} = 31.4 t o r r$

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Solids in Liquids

Standard XII Chemistry

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Calculate the vapour pressure of water at 27∘C, when the aqueous tension at 77∘C is 314.1 torr. (Given: Heat of vapourisation of water is nearly 40 kJ/mol) [e−2.3=0.1]

Calculate the vapour pressure of water at $27^{\circ} C$ , when the aqueous tension at $77^{\circ} C$ is $314.1 t o r r$ . (Given: Heat of vapourisation of water is nearly $40 k J / m o l$ ) [ $e^{- 2.3} = 0.1$ ]