Chapter 2 Notes—Changes in Matter 11/05/12

Section 1—Solids, Liquids, and Gases.  Solid – has a definite shape and volume. Particles are packed tightly together and stay in a one fixed position. Particles are packed tightly together and stay in a one fixed position.

2 types of Solids  Crystalline solids – particles form a regular, repeating pattern, creating crystals. Examples – Salt, sugar, sand, and snow.

2 types of Solids  Amorphous solids – particles are not arranged in a regular pattern. Examples – plastics, rubber, and glass. Examples – plastics, rubber, and glass.

Liquids  Liquids – have no definite shape, but do have a definite volume.

How particles move in a liquid?  Fluid – “a substance that flows”. A liquid that can flow from one place to another.  Viscosity – the resistance of a liquid to flow.

Viscosity  Liquids with high viscosity flow slowly. Syrup and honey are examples of high viscosity.  Liquids with low viscosity flow quickly. Water and vinegar are examples of low viscosity.

Gas  Gas – has no definite shape or volume. Particles take up any space they are given.

Section 2  Gas and volume = because gases fill up the space they are given, their volume will always be the same as the volume of their container.

Measuring Gases  Temperature – is a measure of average energy of motion of the particles of a substance. The faster the particles are moving, the more energy, greater the temperature.

Measuring Gases  Pressure – is the force of its outward push divided by the area of the walls of the container. P = force/areakilopascals kPa P = force/areakilopascals kPa

Boyle’s Law  Boyle’s law – when the pressure of a gas is increased at a constant temperature, the volume of the gas decreases. When the pressure decreases the volume increases. Boyle’s law Boyle’s law

Temperature and Pressure  When the temperature of a gas at a given volume is increased, the pressure increases. temperature  When the temperature of a gas at a given volume is decreased, the pressure decreases.

Charles Law  Charles Law – when the temperature of a gas is increased at a constant pressure, its volume increases. When the temperature is decreased the volume decreases. Charles Law Charles Law

Section 4 – Changes  Physical Change – the form changes but not into a new substance.  Chemical Change – new substance with new properties.

Law of Conservation of Energy  Law of conservation of energy – in every physical or chemical change, the total amount of energy stays the same.

Changing Liquids and Solids  Melting – the change in a state from a solid to a liquid.  Freezing – changing from a state of liquid to solid.

Changing Liquids and Gases  Vaporization – occurs when a liquid gains enough energy to become a gas. There are two types: There are two types: EvaporationEvaporation BoilingBoiling

Changing Liquids and Gases  Evaporation – when a liquid changes to a gas only on the surface of the liquid.  Boiling – when a liquid changes to a gas inside a liquid as well as at the surface. Boiling Boiling

Changing Liquids and Gases  Condensation – the opposite of vaporization. When a gas loses enough energy to become a liquid.

Changing from Solid to Gas  Sublimation – When the surface particles of a solid gain enough energy to become a gas.

Changing from Solid to Gas

Chemical Reactions  Chemical Reaction – one substance changes into two or more other new substances. Example: Baking a cake. Example: Baking a cake.