1
What does temperature measure?
Average kinetic energy of particles
Which has a higher melting point: water or gallium?
water
How do intermolecular attractions affect melting and boiling points?
Stronger attractions → higher melting and boiling points
On a heating curve, what does a flat (horizontal) segment indicate?
A phase change where temperature remains constant.
What is the difference between evaporation and boiling?
vaporation occurs at the surface; boiling occurs throughout the liquid
What is the term for the change from gas to liquid?
condensation
______________________ is the total internal energy that depends on number of particles, state, and temperature
thermal energy
During melting or freezing, what happens to the temperature of the substance?
it remains constant while the phase change occurs.
Rank the average speeds of particles in solid, liquid, and gas at the same temperature from fastest to slowest
What happens to the potential energy of particles when a substance changes from liquid to gas?
The potential energy increases as particles move farther apart and intermolecular attractions are overcome.
how you could increase the thermal energy of a system without changing its temperature?
increase particles by adding more of the substance at the same temp
or change state to a state of matter that has higher PE (solid to liquid; liquid to gas)
True or false: temperature is the same thing as thermal energy
false
it also depends on number of particles and state
Explain how particle potential and kinetic energy change during a heating curve when a substance goes from solid → liquid → gas.
During temperature increases (within a phase) kinetic energy increases; during phase changes temperature stays constant while potential energy increases (solid→liquid→gas) as bonds/attractions are overcome.
In what state are particles close together but can slide past each other freely?
liquid
According to the heating curve for water, what happens to temperature when water is changing from liquid to gas?
t remains constant during the liquid→gas phase change.
When energy is added to a substance already at its boiling point, what happens to the temperature and why?
The temperature remains constant until all liquid becomes gas; added energy goes into increasing potential energy to separate particles
Which state has particles closely packed in a fixed arrangement?
solid