Types of Phase Changes
What must you add OR take away from a substance to cause it to change phase?
Energy
What are the THREE main phases all substances can be found in?
solid, liquid, gas
Define the vocabulary word freedom of movement.
The way molecules in a substance move around relative to each other.
When do the molecules of a substance have kinetic energy?
When they are moving!
TRUE or FALSE. The molecules that make up ALL substances are ALWAYS moving no matter what phase the substance is in.
TRUE
What type of phase change has occurred if the substance starts out as a SOLID has energy ADDED to it and becomes a liquid?
Melting
How do molecules move as a SOLID? What are THREE macro-scale qualities of a solid?
Molecules vibrate in place. Macro-scale qualities of a solid: they are rigid, they have a specific shape, they keep their shape.
What TWO things help us to determine if the freedom of movement of a substance has changed?
The speed of the molecules and the space between the molecules.
How do we measure the amount of kinetic energy a substance has?
By measuring its temperature.
If I start off with a GAS and I transfer ENERGY OUT of the substance what will happen to the substance's KINETIC ENERGY and SPEED of the molecules?
The kinetic energy of the substance will decrease the molecules will move less and they will move slower.
What type of phase change has occurred if a substance starts out as a LIQUID has energy ADDED to it causing it to become a GAS?
Evaporation
How do molecules move as a LIQUID? What are THREE macro-scale qualities of a liquid?
Molecules move around each other. Macro scale qualities: flows, stays at the bottom of the container, takes the shape of the container.
If I start out with a GAS and I TAKE AWAY ENERGY from it causing it to CONDENSE and become a LIQUID. Did the substance's freedom of movement increase OR decrease? How do you know?
The substance's freedom of movement DECREASED. I know this because taking energy away from the substance will cause its molecules to move slower and there will be less space between the molecules.
FILL IN THE BLANKS. When we increase the temperature of the substance, the substance will get __________ and the substance will have ___________ kinetic energy.
hotter(warmer), more
If I start off with a GAS and I transfer ENERGY OUT of the substance what will happen to the substance's FREEDOM OF MOVEMENT and TEMPERATURE OF THE SUBSTANCE?
The substances freedom of movement will decrease the molecules will move slower and the space between the molecules will decrease. The temperature will decrease and the substance will be colder.
What type of phase change has occurred if the substance starts out as a gas and has energy TAKEN AWAY from it causing it to become a LIQUID?
Condensation
How do molecules of a GAS move? What are THREE macro-scale qualities of a gas?
Molecules spread out and move away from each other. Macro-scale qualities: most are invisible to the human eye, no specific shape, expand to fill the container that they are in.
If I start out with a SOLID and I ADD ENERGY to it causing it to MELT and become a LIQUID. Did the substance's freedom of movement increase OR decrease? How do you know?
The substance's freedom of movement increased. I know this because when you add energy to a substance this will cause the molecules to move faster and there will be more space between the molecules.
FILL IN THE BLANKS. When we decrease the temperature of the substance, the substance will get __________ and the substance will have _____________ kinetic energy.
colder, less
If I start off with a SOLID and I transfer ENERGY INTO the substance what will happen to the substance's kinetic energy and speed of the molecules?
The kinetic energy of the substance will increase the molecules of the substance will move more and they will move faster.
What type of phase change has occurred if the substance starts out as a LIQUID has energy TAKEN AWAY from it causing it to become a SOLID?
Freezing
FILL IN THE BLANK. Changes to a substance's appearance during a phase change that can be observed at the macro-scale, can be explained by changes in the way molecules _________________ at the molecular scale.
move
If I start out with a LIQUID and I ADD ENERGY to it causing it to EVAPORATE and become a GAS. Did the substance's freedom of movement increase OR decrease? How do you know?
The substance's freedom of movement increased. I know this because adding energy to the substance will cause its molecules to move faster and there will be more space between the molecules.
FILL IN THE BLANKS. When a substance has MORE kinetic energy the molecules of the substance will move _____________ and faster. When a substance has LESS kinetic energy the molecules of the substance will move less and ____________.
more, slower
If I start off with a SOLID and I transfer energy into the substance what will happen to the substance's freedom of movement and temperature?
The freedom of movement of the substance will increase causing the molecules to move faster and the space between the molecules to increase. The temperature will increase and the substance will become hotter.