3:4 Phase Changes

Answer to learning target 1

Amount of energy it takes to turn solid into a liquid or the amount of energy it takes to turn gas into the liquid, or liquid to gas.

Water is initially present in a state where its molecules are far apart. During a change of state, its molecules slow down. Which change of state has most likely taken place? A from a gas to a liquid B from a liquid to a gas C from a solid to a liquid D from a gas to a plasma

from a gas to a liquid

Which best explains the relationship between evaporation and temperature? A A liquid evaporates slower at lower temperatures because the molecules are more spread apart and are not pushed as easily from the liquid's surface. B A liquid evaporates faster at lower temperatures because the attractions are decreased and more particles can escape the surface of the liquid. C A liquid evaporates slower at higher temperatures because the vapor pressure of the liquid is higher, so fewer molecules can escape the surface. D A liquid evaporates faster at higher temperatures because more particles have a higher speed and can overcome attractions in the liquid.

A liquid evaporates faster at higher temperatures because more particles have a higher speed and can overcome attractions in the liquid.

A solid substance turns into a liquid. Which best describes this change? A A substance that has a specific volume changes to a substance that has a specific shape. B A substance that has a specific volume changes to a substance that has a different volume. C A substance that has a specific shape and volume changes to a substance that has a specific volume. D A substance that has a specific volume changes to a substance that has a specific shape and volume.

A substance that has a specific shape and volume changes to a substance that has a specific volume.

Learning Targets:2

Describe the energy changes that happen during changes of state.

Which energy change occurs during boiling? A Some heat energy of the substance is lost. B Heat energy of the substance remains the same. C Most heat energy of the substance is lost. D Heat energy is absorbed by the substance.

Heat energy is absorbed by the substance.

Which energy change occurs during boiling? A Some heat energy of the substance is lost. B Heat energy of the substance remains the same. C Most heat energy of the substance is lost. D Heat energy is absorbed by the substance.

Heat energy is absorbed by the substance.

Which best describes the energy change that takes place during the deposition? A Heat energy is released by the substance. B Heat energy is maintained by the substance. C Heat energy is slowly gained by the substance. D Heat energy is quickly absorbed by the substance.

Heat energy is released by the substance.

Answer to learning target 2

If heat is coming into a substance during a phase change, then this energy is used to break the bonds between the molecules of the substance.

"When nitrogen is liquefied, heat is released." Is this statement true or false? A It is false because nitrogen absorbs heat when it is liquefied. B It is false because nitrogen cannot absorb enough heat to liquefy. C It is true because heat is released when gas changes to a liquid. D It is true because heat is released when liquid changes to a gas.

It is true because heat is released when gas changes to a liquid.

Consider the temperature versus time graph below. At what temperature is the boiling point of this substance? A at 0°C B between 0°C and 100°C C at 120°C D above 120°C

at 120°C

When does carbon dioxide absorb the most heat energy? A during freezing B during deposition C during sublimation D during condensation

during sublimation

Which example involves a phase change in which heat energy is released by the substance? A freezing ice cream B cooking a pot of soup C melting ice under sunlight D watching frost disappear into the air

freezing ice cream

Learning Targets:1

Describe phase changes in terms of kinetic-molecular theory.