Suppose you have two colorless molecular liquids, one boiling at - 84 °C, the other at 34 °C, and both at atmospheric 6 pressure. Which of the following statements is correct? For each statement that is not correct, modify the statement so that it is correct. (e) At - 84 °C both liquids have vapor pressures of 760 mm Hg.

Key Concepts

Boiling Point and Vapor Pressure

The boiling point of a liquid is the temperature at which its vapor pressure equals the atmospheric pressure. At this point, the liquid transitions to a gas. For the liquid boiling at -84 °C, it will have a vapor pressure of 760 mm Hg at that temperature, but the other liquid, boiling at 34 °C, will not necessarily have the same vapor pressure at -84 °C.

Vapor Pressure and Temperature Relationship

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid at a given temperature. As temperature increases, the vapor pressure of a liquid also increases. Therefore, at -84 °C, the vapor pressures of both liquids will be lower than 760 mm Hg, making the statement about both having the same vapor pressure at that temperature incorrect.

Atmospheric Pressure

Atmospheric pressure is the pressure exerted by the weight of the atmosphere at a given location, typically measured at sea level as 760 mm Hg. This pressure is crucial for understanding boiling points and vapor pressures, as liquids will boil when their vapor pressure matches this atmospheric pressure. The statement in question fails to consider that vapor pressures vary with temperature and are not constant across different liquids.