What kind of boiling points does a substance with high vapor pressure tend to have?

What kind of boiling points does a substance with high vapor pressure tend to have?

• A. High vapor pressure corresponds to low boiling points.
• B. High vapor pressure corresponds to high boiling points.
• C. They have no boiling point.
• D. Boiling point is unrelated to vapor pressure.

Answer: (A)

High vapor pressure means a liquid tends to escape into the gas phase readily, even at lower temperatures. Boiling occurs when the vapor pressure of the liquid equals the surrounding atmospheric pressure. So if a substance already has a high vapor pressure, you reach that atmospheric pressure at a cooler temperature, giving you a lower boiling point. For example, volatile solvents like acetone boil at relatively low temperatures because their vapor pressure is high. Water, with a lower vapor pressure at the same temperature, boils only when heated to a higher temperature. Therefore, high vapor pressure corresponds to a low boiling point.

High vapor pressure means a liquid tends to escape into the gas phase readily, even at lower temperatures. Boiling occurs when the vapor pressure of the liquid equals the surrounding atmospheric pressure. So if a substance already has a high vapor pressure, you reach that atmospheric pressure at a cooler temperature, giving you a lower boiling point. For example, volatile solvents like acetone boil at relatively low temperatures because their vapor pressure is high. Water, with a lower vapor pressure at the same temperature, boils only when heated to a higher temperature. Therefore, high vapor pressure corresponds to a low boiling point.