We’re being asked to **determine the heat of vaporization** of a substance. We’re given the vapor pressure at two different temperatures. For this problem, we can use the ** Clausius-Clapeyron Equation**:

where:

**P _{1}** = vapor pressure at T

**P _{2}** = vapor pressure at T

**ΔH _{vap}** = heat of vaporization (in J/mol)

**R** = gas constant (8.314 J/mol•K)

**T _{1} and T_{2}** = temperature (in K).

An unknown liquid has a vapor pressure of 88 mmHg at 45 ^{◦}C and 39 mmHg at 25^{◦}C. What is its heat of vaporization?

1. 32 kJ/mol

2. 2000 J/mol

3. 32000 kJ/mol

4. 2000 kJ/mol

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What scientific concept do you need to know in order to solve this problem?

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What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Sutcliffe's class at TEXAS.