Phase Transitions (10.3) Flashcards
- Define phase transitions and phase transition temperatures. - Explain the relation between phase transition temperatures and intermolecular attractive forces. - Describe the processes represented by typical heating and cooling curves, and computer heat flows and enthalpy changes accompanying these processes.
What is vaporization?
When a solid or liquid becomes a gas.
What is condensation?
Change from gas phase to liquid phase.
What is dynamic equilibrium?
Is a state in a system where two opposing processes are happening at the same time at the same rate, so there is no overall change in the system.
Example: In a sealed container of water, there is vapor being produced but at the same time vapor is condensing back to liquid in an equal rate, so there is no overall change.
What is vapor pressure?
The gas that has been vaporized into the air of a closed container is vapor pressure. Measured by the pressure the gas has exerted in the container.
When it comes to vapor pressure does it matter on what molecules are made of?
Yes, the way molecules stick together in a liquid affects how easily they can turn into a gas.
Different liquids = different ways of sticking together.
Different liquids = different levels of vapor pressure.
How is vapor pressure affected if molecules in liquid stick together very well?
It’s harder for molecules to escape and become gas if liquid molecules stick very well together. Even if they do escape, there is a chance they will be pulled right back into the liquid (means liquid has low vapor pressure).
What about if molecules in a liquid don’t stick together very well?
Pretty much means the opposite, gases are formed more easily and the liquid has a high vapor pressure (more gas above liquid).
As temperature increase what increases?
Vapor pressure increases.
Define boiling point (in terms of vapor pressure).
Temperature at which vapor pressure equals the external pressure on the liquid.
External Pressure: can vary depending on environment.
High Altitude = External Pressure is Low, so boiling point is lower.
What is normal boiling point (in terms of vapor pressure)?
The temperature at which liquid boils when the external pressure is 1 atmosphere (atm) or 101.3 kilopascals (kPa).
It is also a standard pressure used to compare boiling points of different types of liquids.
Define melting (in terms of states of matter)
Melting is added energy to the atoms/molecules/ions and the solid gets hotter to where it turns into a liquid. The forces gets weaker while the atoms/molecules/ions become more active.
Define freezing (in terms of states of matter)
Less molecular activity of atoms/molecules/ions in fixed position and starts to slowly stop moving and the intermolecular forces is stronger as freezing point is reached. (0 Celsius or 32 Fahrenheit under normal atmospheric pressure).
What is sublimation?
A process where the solid becomes a gas without needing to go through the liquid phase to turn into a gas.
What is deposition?
The complete opposite of sublimation but same process, where the gas becomes a solid without needing to go through the liquid phase.
