Solids, Liquids, and Gases
Which state of matter has a definite shape and definite volume?
Solid
What is the phase change from solid to liquid called?
Melting
What happens to particle motion when energy is added?
They move faster and spread out.
Why does water boil at a lower temperature on a mountain?
Lower air pressure.
Why does condensation form on a cold soda can?
Water vapor cools, loses energy, and turns into liquid.
Which state of matter has particles that are close together but slide past one another?
Liquid
What is the reverse of melting?
Freezing
What happens to particle motion when energy is removed?
They slow down and get closer together.
Why does boiling point increase under higher pressure?
Particles need more energy to escape into gas phase.
Why does a balloon shrink in the freezer?
Gas particles slow, move closer, and reduce pressure.
Which state of matter has no definite shape or volume?
Gas
What is sublimation?
Solid → Gas (skips liquid)
Why is evaporation considered a cooling process?
Fastest particles escape, leaving cooler ones behind.
What happens to gases when pressure increases at constant temperature?
Particles are forced closer together.
Why does ice melt faster in warm water than in cold water?
More energy is transferred in warm water.
Compare the particle motion in solids vs gases.
Solids vibrate in place; gases move freely and rapidly.
What is deposition?
Gas → Solid (skips liquid)
Compare boiling and evaporation.
Evaporation at surface at any temp; boiling throughout liquid at specific temp.
What happens to gases when pressure decreases at constant temperature?
Particles spread out and expand.
Why does frost form on a window in winter?
Deposition — water vapor turns directly to solid.
Why can gases be compressed but solids cannot?
Gas particles are far apart; solid particles are tightly packed.
What happens at the triple point?
Substance exists as solid, liquid, and gas simultaneously.
Explain why melting and freezing occur at the same temperature.
Both involve the same energy threshold, just energy in vs energy out.
Why would boiling water on Venus require more heat than on Earth?
Venus has much higher pressure, so water needs more energy to boil.
How do astronauts use knowledge of gases in space?
Spacecraft control air pressure and oxygen for breathing and safety.