Phase Change Detective
What phase change occurs when a solid becomes a liquid?
What is melting?
What happens to the motion of particles when energy is added?
Answer: Their particles move faster.
On a heating curve, what do the sloped lines represent?
Answer: Increasing kinetic energy/temperature
According to Kinetic Molecular Theory, how do gas particles move?
Answer: They move in constant, random, straight-line motion.
What phase change occurs when a gas changes into a liquid?
What is condensation?
Temperature is related to the average ______ energy of particles.
Answer: Kinetic
On a heating curve, what do the flat lines represent?
Answer: A phase change
What happens when gas particles collide with each other or the walls of their container?
Answer: Energy is transferred, but there is no overall loss of energy. These are called elastic collisions.
A puddle of water disappears into the air. What phase change is occurring?
Answer: What is vaporization?
Which has particles with more potential energy: a solid or a gas?
Answer: A gas
During a flat portion of a heating curve, where is the energy going if temperature isn't increasing?
Answer: It is increasing the potential energy of the particles and changing their arrangement/spacing.
Are gas particles close together or very far apart?
Answer: They are very far apart, with lots of empty space between them.
A substance changes directly from a solid into a gas without becoming a liquid first. What is this called?
Answer: What is sublimation?
During a phase change, does the temperature of a substance change?
Answer: No. The temperature remains constant during the phase change.
A sample is being heated, but its temperature stays the same for several minutes. What is most likely happening?
Answer: The substance is undergoing a phase change.
According to Kinetic Molecular Theory, do gas particles attract each other?
Answer: No. The model assumes gas particles do not attract one another.
A gas changes directly into a solid without becoming a liquid. What is this phase change called?
Answer: What is deposition?
Explain why gas particles have more potential energy than particles in a solid.
Answer: Gas particles are farther apart, so more energy is stored in their separation.
Why is the boiling/condensation portion of a heating or cooling curve longer than the melting/freezing portion?
Answer: Particles must move farther apart or closer together when changing between liquid and gas than when changing between solid and liquid.
A gas is heated. Using Kinetic Molecular Theory, explain what happens to its particles.
Answer: The particles gain kinetic energy and move faster.