Chapter 8 States of Matter

8.1 Three States of Matter States of Matter- These are physical forms in which a substance can exist. Let’s use water as an example. Solid water is called ice. Liquid water is called water. Gaseous water is called water vapor. Particles of Matter Matter is made up of tiny particles called atoms and molecules. These particles can only be seen with a very powerful microscope. Atoms and molecules are always in motion bumping into each other.

Solids Solid- particles are packed closely together and can only vibrate in place. All solids have a definite shape and volume.

Two types of solids: Crystalline- These solids have an orderly arrangement of particles in a repeating pattern. Examples include iron, diamond, ice, crystal Amorphous- These solids do not have a special arrangement. Examples include glass, rubber, wax.

Liquids Liquid- particles are close together, but they have enough room to slide past one another. Liquids have a definite volume but they take the shape of the container they are in.

Liquids have several properties that make them unique. Surface tension- A force that acts on the particles at the surface of the liquid. This causes some particles to form spherical drops like beads. Water has a high surface tension while rubbing alcohol has a low surface tension. Viscosity- the resistance of a liquid to flow. The stronger the attractions between the molecules, the more viscous the liquid is. Honey has a high viscosity. Water has a low viscosity.

Gas Gas- particles are far apart and move independently. Gases do not have a definite shape or a definite volume. They fill the container.  

8.2 Changes in State Change of state- The change of a substance from one physical state to another ALL STATE CHANGES ARE PHYSICAL CHANGES. Particles of a substance have different amounts of energy depending on the state of the substance. Particles have different amounts of energy in different states. Solids – low energy Liquids – medium Gases – high YOU MUST ADD OR REMOVE ENERGY TO CHANGE STATES.

Changes in State Melting Freezing Vaporization (evaporation) 4. Condensation 5. Sublimation 6. Deposition Vaporization Condensation Sublimation Deposition Freezing Melting

Melting: Solid to Liquid Melting- change in state from solid to liquid. Adding energy to ice raises its temperature. As the temperature increases, the particles energy increasaes When a certain temperature is reached (0°C) the ice melts Melting Point - The temperature at which a substance changes from a solid to a liquid. Melting point is a physical property. Different substances have different melting points. Melting is endothermic- energy is gained by the substance

Freezing: Liquid to Solid Freezing- change in state from a liquid to solid. Freezing point- The temperature at which liquid changes into a solid. Freezing is the reverse of melting, so they occur at the same temperature. Any solid is in the frozen state! Freezing is exothermic- energy is removed from the substance

Vaporization: Liquid to Gas Vaporization- change in state form a liquid to gas. Vaporization can occur at the surface of a liquid that is below the boiling point. Sweat will evaporate off your skin and spilled water will evaporate off a counter. Boiling- Change of a liquid to a vapor, or gas, within the liquid. This occurs when the pressure inside the bubbles equals the outside pressure on the bubbles. Boiling point- temperature at which a substance boils Boiling requires energy so it is endothermic

Vaporization Boiling Evaporation

Effects of Pressure on Boiling Point Water boils at 100ºC, but only at sea level because of atmospheric pressure. Atmospheric pressure is caused by the gases that make up the atmosphere. The higher you go above sea level, the fewer air particles there are above you so atmospheric pressure is less. In Denver, the mile high city, water boils at 94o C.

Condensation: Gas to Liquid Condensation- change of state from a gas to liquid. Condensation point- temperature at which a substance goes from a gas to a liquid. Condensation is the reverse of vaporization, so they occur at the same temperature. For a gas to become a liquid, large numbers of particles must clump together. Energy must be removed - exothermic

Sublimation: Solid to Gas Dry ice (carbon dioxide) changes directly from a solid to a gas. Sublimation- the change from a solid to a gas without being a liquid The substance must gain a lot of energy for this to occur, therefore it is endothermic.

Deposition: Gas to Solid Deposition: the change from a gas to a solid without being a liquid Frost changes directly from gas to solid Deposition is an exothermic change because a lot energy must be removed.

Change in temperature vs. Change in state When substances gain or lose energy, the temperature will change or remain the same. As the temperature rises, the particles gain energy. Once the particles have enough energy, the state will change. At this point the temperature will remain until the state change is complete. Boiling water will remain at 100oC until it all evaporates.

Change in temperature vs. Change in state Gas vaporization 1000c Condensation Liquid melting 00c Solid Freezing

Partner Share Neatly and in your own words, Write at least 8 lines describing the difference between boiling and evaporation. Be sure to give an example of where there may be different boiling points for the same substance.

8.3 Behavior of Gases Describing Gas Behavior Gases behave differently from solids and liquids. Gases have large amounts of empty space between molecules.

Temperature of Gases Temperature is a measure of how fast the particles in an object are moving around. On a hot day, particles move faster and hit the inside walls of a balloon more often. Thus, increasing energy and pushing on the walls. On a cold day, particles have less energy They do not push very hard on the walls of the balloon.

Volume Volume a measure of the size of a body or region in three dimensional space Particles of a gas spread out so the volume of any gas depends on the container that the gas is in.

Pressure Pressure is the amount of force exerted per area on a surface This is the amount of times the particles of a gas hit the inside of their container. If you compare a basketball and a beach ball, you will notice the basketball is very firm. It has a greater pressure. The beach ball has a much lower pressure.

Gas Behavior Laws Scientists found that temperature, pressure, and volume of a gas are related. Changing one of the factors will affect the others. Boyles’s Law- Robert Boyle discovered if you have a fixed amount of gas at a constant temperature, the volume of the gas is indirectly related to the pressure. If you increase the pressure, then you will decrease the volume by the same amount. Ex. Diver blowing an air bubble under the water, when the bubble reaches the surface, the bubbles volume has greatly increased. Think: Boyle is the vice president (VP)(volume, pressure)

Gas Behavior Laws Ex. Taking a balloon outside into the cold Charles’ Law- If you have a fixed amount of gas at a constant pressure, the volume of the gas will be directly related to the temperature. If the temperature increases, the volume will increase by the same amount. Ex. Taking a balloon outside into the cold Think: Charlie Brown is on TV (temperature, volume)

Gas Behavior Laws Guy Lusaac’s Law -If you have a fixed amount of gas at a constant volume, the pressure of the gas will be directly related to the temperature. If the temperature increases, the pressure will increase by the same amount. Think: G lives in a TP (temperature, pressure)

Gas Behavior Laws Boyle ↑ ↓ Charles Guy - Lussac Temperature Pressure Volume Boyle _______________ ↑ ↓ Charles Guy - Lussac ______________