High School

The vapor pressure of ethanol is 100 torr at 35 °C. If the enthalpy of vaporization (\( \Delta H_{\text{vap}} \)) for ethanol is 39.3 kJ/mol, what is the vapor pressure of ethanol at 65 °C?

Choose one of the following answers:

A. 130 torr
B. 260 torr
C. 390 torr
D. 650 torr
E. 760 torr

Answer :

Final answer:

The vapor pressure of ethanol at 65 °C is approximately 130 torr.

Explanation:

To find the vapor pressure of ethanol at 65 °C, we can use the Clausius-Clapeyron equation:

[tex]ln(P2/P1) = (-ΔHvap/R) * (1/T2 - 1/T1)[/tex]

Where:

  • P1 is the vapor pressure at the initial temperature (35 °C) = 100 torr
  • P2 is the vapor pressure at the final temperature (65 °C)
  • ΔHvap is the enthalpy of vaporization = 39.3 kJ/mol
  • R is the ideal gas constant = 8.314 J/(mol·K)
  • T1 is the initial temperature in Kelvin (35 °C + 273.15)
  • T2 is the final temperature in Kelvin (65 °C + 273.15)

Let's calculate the vapor pressure at 65 °C:

[tex]ln(P2/100) = (-39.3 * 10^3 / 8.314) * (1/(65 + 273.15) - 1/(35 + 273.15))[/tex]

Solving for P2:

[tex]P2 = 100 * e^((-39.3 * 10^3 / 8.314) * (1/(65 + 273.15) - 1/(35 + 273.15)))[/tex]

Calculating the value:

P2 ≈ 130 torr

Learn more about vapor pressure and temperature here:

https://brainly.com/question/32766793

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