Quiz: Gen Chem 2 phase diagrams and vapor pressure

What is a phase diagram?

A graphical representation showing the phases of a substance at varying temperatures and pressures.

Label the three main phases on a phase diagram.

- Solid - Liquid - Gas

True or False: Phase diagrams can only display one substance.

False. Phase diagrams can represent mixtures and multiple substances.

What does the triple point represent?

The unique set of conditions where solid, liquid, and gas coexist in equilibrium.

Identify the axis of a phase diagram.

- X-axis: Temperature - Y-axis: Pressure

Fill in the blank: The boundary lines on a phase diagram indicate __________.

the conditions at which two phases coexist.

Compare the critical point and triple point.

Critical point: End of liquid-gas boundary. Triple point: All phases in equilibrium.

What is a phase boundary?

A line on a phase diagram separating different phases, indicating equilibrium conditions.

Cause → Effect: Increase temperature above the boiling point results in __________.

a transition from liquid to gas.

What happens at the melting point on a phase diagram?

Solid and liquid phases coexist at equilibrium.

True or False: The slope of the solid-liquid line indicates how pressure affects melting.

True. A positive slope means increased pressure raises the melting point.

What occurs in the supercritical region?

Distinct liquid and gas phases do not exist; properties of both are exhibited.

Identify the phase where molecules are most energetic:

Gas phase, due to higher kinetic energy.

Fill in the blank: The vaporization line separates __________ from __________.

liquid; gas

What defines the vapor pressure of a substance?

The pressure exerted by a vapor in equilibrium with its liquid at a given temperature.

Short example: Describe a phase change from solid to gas.

Sublimation occurs when a solid transitions directly to gas, like dry ice.

What is vapor pressure?

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase. It reflects the tendency of particles to escape from the liquid phase into the vapor phase.

True or False: Vapor pressure increases with temperature.

True. As temperature increases, more molecules have sufficient energy to escape the liquid phase, resulting in higher vapor pressure.

How does vapor pressure relate to boiling point?

A liquid boils when its vapor pressure equals the atmospheric pressure. Higher vapor pressure at a given temperature means a lower boiling point.

Fill in the blank: Vapor pressure is influenced by __________.

Temperature and intermolecular forces.

Comparing liquids: Which has higher vapor pressure, ethanol or water?

Ethanol has higher vapor pressure than water at the same temperature due to weaker hydrogen bonding.

What does the Clausius-Clapeyron equation represent?

It describes the relationship between vapor pressure and temperature: $\displaystyle \frac{dP}{dT} = \frac{L}{T imes riangle V}$, where L is the latent heat of vaporization.

Which phase has the highest kinetic energy?

Gas phase. Gas molecules have much higher kinetic energy than those in the liquid or solid phases.

Effect of lowering temperature on vapor pressure?

Lowering temperature decreases vapor pressure as fewer molecules have enough energy to escape the liquid phase.

Question: Does adding a non-volatile solute affect vapor pressure?

Yes, it decreases vapor pressure due to the solute particles occupying space, reducing the number of solvent molecules that can escape.

What is the significance of the critical point?

At the critical point, liquid and vapor phases are indistinguishable. The vapor pressure at this point is called the critical pressure.

Cause → Effect: Increased molecular weight in liquids?

Cause: Increased molecular weight; Effect: Generally leads to lower vapor pressure due to stronger intermolecular forces.

What is the vapor pressure of pure water at 100°F?

Approximately 0.3 atm. Vapor pressure varies with temperature, so it's essential to refer to tables for accuracy.

True or False: Vapor pressure is constant for a given substance.

False. Vapor pressure changes with temperature; it increases as temperature rises.

What happens to vapor pressure in a closed container over time?

It reaches equilibrium where the rate of evaporation equals the rate of condensation, stabilizing the vapor pressure.