At 50.14k a substance has a vapor pressure of 258.9 torr. calculate its heat of vaporization in kj/mol if it has a vapor pressure of 277.5 torr at 161.2k

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Chemistry

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29 June, 23:43

At 50.14k a substance has a vapor pressure of 258.9 torr. calculate its heat of vaporization in kj/mol if it has a vapor pressure of 277.5 torr at 161.2k

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Marcel Dawson · Answer 1

T₁ = 50,14 K.

p₁ = 258,9 torr.

T₂ = 161,2 K.

p₂ = 277,5 torr.

R = 8,314 J/K·mol.

Using Clausius-Clapeyron equation:

ln (p₁/p₂) = - ΔHvap/R · (1/T₁ - 1/T₂).

ln (258,9 torr/277,5 torr) = - ΔHvap/8,314 J/K·mol · (1/50,14 K - 1/161,2 K).

-0,069 = - ΔHvap/8,314 J/K·mol · (0,0199 1/K - 0,0062 1/K).

0,0137·ΔHvap = 0,573 J/mol.

ΔHvap = 41,82 J.