Find the temperature at which ethanol boils on a day in the mountains when the barometric pressure is 547 mmHg.(Given: The heat of vaporization of ethanol is 39.3 kJ/mol; the normal boiling point of ethanol is 78.3°C.)
A)76.5°C
B)69.9°C
C)10.0°C
D)77.9°C
E)74.6°C

Question

Quizplus · Accepted Answer

The boiling point of a liquid decreases with a decrease in atmospheric pressure. Using the Clausius-Clapeyron equation, which relates the change in vapor pressure with temperature, we can calculate the boiling point at a lower pressure. Given the normal boiling point and the heat of vaporization, the calculation shows that ethanol boils at approximately 69.9°C at 547 mmHg.

Find the Temperature at Which Ethanol Boils on a Day