Question

what is the ultimate goal of measuring the vapor pressure of ethanol at different temperatures? select one: to calculate the heat of vaporization (δhvap) of ethanol. to prove that ethanol is a volatile liquid. to determine the boiling point of ethanol. to find the universal gas constant, r.

Explanation:

Step1: Analyze the problem context

The problem is about the goal of measuring ethanol vapor pressure at different temperatures. The Clausius - Clapeyron equation $ln(P_2/P_1)=\frac{\Delta H_{vap}}{R}(\frac{1}{T_1}-\frac{1}{T_2})$ relates vapor pressure ($P$), heat of vaporization ($\Delta H_{vap}$), temperature ($T$) and the universal gas constant ($R$). Measuring vapor pressures at different temperatures is often used to calculate the heat of vaporization of a substance.

Step2: Evaluate each option

• Proving ethanol is a volatile liquid is not the main goal as it is already known and not directly related to measuring vapor - pressure at different temperatures.
• Determining the boiling point of ethanol is not the main goal. While boiling point is related to vapor pressure, the focus here is on the process of measuring vapor pressures at different temperatures, which is more related to calculating $\Delta H_{vap}$.
• Finding the universal gas constant $R$ is not the goal as $R$ is a known constant and not determined by measuring ethanol vapor pressure at different temperatures.
• Calculating the heat of vaporization ($\Delta H_{vap}$) of ethanol is the ultimate goal as it can be determined from the relationship between vapor pressure and temperature data using the Clausius - Clapeyron equation.

Answer:

To calculate the heat of vaporization ($\Delta H_{vap}$) of ethanol.