Chapter 17 - Change of Phase Flashcards
Explain Evaporation
Evaporation is a cooling process moving from liquid to gas. The molecules within a liquid have lots of KE and are moving around violently (gaining and losing energy) against each other. The molecules that gain more KE than they lose break through the surface of the liquid and go into the air above. The molecules that are left in the liquid are the ones that lost more KE than they gained, hence they are cooler. So, the liquid has a cooler temperature after evaporation.
What is Sublimation?
Sublimation is going straight from a solid to a gas. An example could be snow on a hot day.
What does “billiard-ball physics” mean?
“Billiard-ball physics” is when balls are bumping into each other and are gaining and losing KE.
What is the cause of almost 90% of Earth’s atmosphere?
Evaporation!
Explain Condensation
Condensation is the opposite of Evaporation. It is a warming process going from gas to liquid. During condensation, the gas (air) molecules are attracted to the molecules of the liquid. The molecules that LOSE more KE leave the air and become part of the liquid. The molecules that GAIN more KE remain as gas molecules, hence making the gas (air) warmer.
What is steam?
Steam is water vapor. It forms at temperatures of 100 degrees Celsius or greater.
What is Humidity?
Humidity is how we measure the water vapor in the air. There is always SOME. Weather people use “relative humidity”.
What is Saturation?
Saturation is when air contains as much vapor as it possibly can.
What is Boiling?
Boiling is when change occurs throughout a liquid, not just at the surface.
What does Boiling depend on?
Temperature & Pressure
At what temperature does water boil? What causes it to boil below and above that temperature?
Water boils at 100 degrees Celsius. Below 100 degrees Celsius, pressure must decrease. Above 100 degrees Celsius, pressure must increase.
What causes high temperatures?
High pressure causes high temperatures.
Explain Melting
Melting is the process where you go from a solid to a liquid. The molecules heat up and move so violently that they can no longer hold on to each other. This is the opposite of Freezing.
Explain Freezing
Freezing is the process where you go from a liquid to a solid. The molecules cool (because KE is withdrawn from the liquid) and move so slowly that they are affected by cohesion. This is the opposite of Melting.
What is Regelation?
Regelation is a property of water. It is the special occurrence where water melts then refreezes again.
