Changes of State Solids, Liquids, and Gases

Solid A rigid collection of particles that has a definite shape and volume. Particles are packed closely together and the attractive forces keep them from moving around They can only vibrate in place.

Crystal Type of solid with particles that are arranged in a repeating pattern. Examples: salt, rocks, minerals Water takes the form of a solid when frozen.

Fluids Substances that contain particles which are free to move about relative to one another. Particles are not closely packed so they can flow and change shape.

Liquid A fluid that can change shape, but maintains a constant volume. The attractive forces are not as strong as in solids, so there is more freedom for the particles to move around. However there is not much space between the particles, which explains why the volume will not decrease substantially when pressure is applied to it.

Gas A fluid that can change both its shape and its volume. Attractive forces are very weak, which causes the particles to be very loosely packed and able to move freely. When pressure is applied, the volume will decrease as the large spaces between the particles shrink.

Plasma Less common state of matter Fluid that consists of ionized atoms, meaning their electrons have been removed. Exists at very high temperatures (interior of stars or bolts of lightning)

Melting Energy taken away Condensing Freezing Evaporating Energy Added

Specific Heat If the same amount of heat is applied to two different substances, they may not experience the same change in temperature. This is due to a difference in the structure of the atoms and molecules that make up the substance. The specific heat (c p ) is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius. Units= J/(g˚C)

Specific Heat Metals tend to have relatively low specific heats. Water has a relatively high specific heat. This is important for life on Earth. If water had a low specific heat, just walking outside on a sunny day might heat water in the cells to a dangerous level.

Specific Heat

Example Problem ◦A 3.61 kg iron skillet initially at 22˚C is heated on a stove to a temperature of 176˚C. How much heat was added to the skillet during this period of time? (specific heat of iron= 0.450J/(g˚C))