Phase Changes

Which of the following is an example of a solid turning into another state of matter?

• water freezing

• tearing a piece of paper

• snow becoming a puddle

• breaking a chair into pieces

What happens to water when it boils?

• It is changed into a solid.

• It is changed into a liquid.

• It is changed into a gas.

• It does not change at all.

Which of the following processes requires thermal energy?

• condensation

• evaporation

• cooling

• freezing

Gallium is a metal that will melt when exposed to the heat of your hand. Which phase change does Gallium undergoes?

• gas to a solid

• solid to a gas

• liquid to a gas

• solid to a liquid

Condensation is a process where gas is changed into a liquid. Which of the following is NOT an example of condensation?

• Smoke from boiling water

• Fog along the highway leading to Baguio.

• Water that collects outside the glass of cold drink.

• Ground-level fog that can be seen on some cold days.

Matter is a substance that has volume and mass. Volume means that it takes up space. Mass is the amount of matter something is made of. Mass can be measured in kilograms, grams or milligrams. Matter comes in three basic states: solid, liquid and gas. A fourth state, plasma, only occurs under very special circumstances.

All substances are made of matter, and matter itself is made up of particles, including single atoms and/or molecules. Because different atoms have varying numbers of protons and neutrons in their nucleus, the matter of different substances contains different masses.

Density is the amount of matter a substance has in a given amount of space. Density is a useful measure because it isn't affected by pressure or temperature. If two objects have equal volume, but one has more mass, the one with more mass is denser. If a something has less density than a liquid, it will float on top of it; if it's denser, it will sink.

Oil is less dense than water. What happens when you mix the two liquids together?

• Oil sinks to the bottom of the container.

• Oil sinks to the bottom of the container.

• The oil floats on top of the water.

• The water turns to gas inside the oil.

Which phase changes require an increase in energy?

• melting and vaporization

• melting and freezing

• melting and condensation

• freezing and condensation

Phase is the state of matter at a given temperature and pressure. There are four possible phases for most substances: solid, liquid, gaseous and plasma. Phase is caused by the force of the attraction between a substance's particles (all substances are composed of molecules and atoms that are actually moving at all times). The phase of a substance changes when a certain amount of energy and/or pressure is applied to it. Take liquid water, for example. If you lower the temperature on liquid water, it freezes to become a solid: ice. Raising the temperature on ice will cause it to melt, returning it to its former phase. In its gaseous state, it is water vapor.

When you melt an ice cube, what is the new phase of the water?

• plasma

• liquid

• gas

• solid

. The drops of water that appear on the outside of a glass of cold juice on a warm day is an example of what phase change of matter?

• Condensation: a gas turning into a liquid.

• Deposition: a gas turning into a solid.

• Evaporation: a liquid turning into a gas.

• Sublimation: a solid turning into a gas.

What phase change does dry ice undergo when it transforms from a solid to a gas, skipping the liquid phase entirely?

• deposition

• melting

• freezing

• sublimation