Chapter 3. States of Matter

Transcription

1 Chapter 3 States of Matter

2 1. Solid 2. Liquid 3. Gas States of Matter Two More (discuss later) Plasma Bose-Einstein condensate

3 States of Matter Solid (definite shape and volume) Particles are tightly packed Stuck to each other in a pattern Vibrate in place Can t t flow Constant volume

4 Liquids Liquid (definite volume, no definite shape) Spread out on their own Particles are tightly packed Able to slide past each other Can flow Constant volume

5 States of Matter Gas(no definite shape, no definite volume) Particles are spread out Flying all over the place Can flow Take the volume of whatever container their in

6 Gases Fill the available space Particles hitting things causes pressure

7 Kinetic Theory Kinetic means motion Three main parts of the theory All matter is made of tiny particles These particles are in constant motion and the higher the temperature, the faster they move At the same temperature, heavier particles move slower.

8 Explaining the Behavior of Gases The constant motion of particles in a gas allows a gas to fill a container of any shape or size 3 Main points on pg. 73

9 Explaining the Behavior of Liquids A liquid takes the shape of its container because particles in a liquid can flow to new locations. The volume of a liquid is constant because forces of attraction keep the particles close together.

10 Explaining the Behavior of Solids Solids have a definite volume and shape because particles in a solid vibrate around fixed locations.

11 3.2 The Gas Laws

12 Pressure Defn.. The result of a force distributed over an area Units: N/m 2 or Pascal ---Pa or KPa Other units: mmhg psi

13 Pressure Collisions between particles of a gas and the walls of the container cause the pressure in a closed container of gas

14 Factors That Affect Gas Pressure Temperature Volume Number of Particles

15 1. Temperature Raising the Temperature will increase the pressure (assuming volume and number of particles are kept constant)

16 2. Volume Reducing the volume of a gas increases its pressure. (assuming temperature and the number of particles are kept constant)

17 3. Number of Particles Increasing the number of particles will increase the pressure (assuming temperature and volume are kept constant)

18 Charles s s Law The volume of a gas is directly proportional to its temperature in Kelvins if the pressure and the number of particles are constant V 1 /T 1 = V 2 /T 2

19 Boyle s s Law The volume of a gas is inversely proportional to its pressure if the temperature and the number of particles are constant P 1 /V 1 = P 2 /V 2

20 The Combined Gas Law P 1 V 1 T 2 = P 2 V 2 T 1

21 3.3 Phase Changes

22 Characteristics of Phase Changes Defn. the reversible physical change that occurs when a substance changes from one state of matter to another

23 Examples Melting Freezing Vaporization Condensation Sublimation Deposition

24 Temperature and Phase Change The temperature of a substance does not change during a phase change

25 Heating Curve for Water

26 Energy and Phase Changes Energy is either absorbed or released during a phase change

27 Endothermic v/s Exothermic Endothermic The system absorbs energy from the surrounding Into the system.from the surroundings Examples Evaporation, melting,

28 Endothermic v/s Exothermic Exothermic The system releases energy to its surroundings Out of the system To the surroundings Examples Condensing, Freezing, Burning

29 Common Terms Fusion Another term for melting Heat of Fusion The energy a substance must absorb in order to change from a solid to a liquid Vaporization Substance changes from a liquid to a gas Heat of Vaporization The energy a substance must absorb in order to change from a liquid to a gas

30 Common Terms Evaporation The process that changes a substance from a liquid to a gas at a temperature below the substance s s boiling point Vapor Pressure The pressure caused by the collisions of a vapor with the walls of its container

31 Boiling When does it occur? When the vapor pressure becomes equal to atmospheric pressure

32 More Terms Condensation The phase change in which a substance changes from a gas or vapor to a liquid Sublimation The phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first Deposition The reverse of sublimation

33

34 The Gas Laws Describe HOW gases behave. Can be predicted by the theory. Amount of change can be calculated with mathematical equations.

35 The effect of adding gas. When we blow up a balloon we are adding gas molecules. Doubling the the number of gas particles doubles the pressure. (of the same volume at the same temperature).

36 Pressure and the number of molecules are directly related More molecules means more collisions. Fewer molecules means fewer collisions. Gases naturally move from areas of high pressure to low pressure because there is empty space to move in.

37 If you double the number of molecules 1 atm

38 If you double the number of molecules You double the pressure. 2 atm

39 4 atm As you remove molecules from a container

40 2 atm As you remove molecules from a container the pressure decreases

41 1 atm As you remove molecules from a container the pressure decreases Until the pressure inside equals the pressure outside Molecules naturally move from high to low pressure

42 Changing the size of the container In a smaller container molecules have less room to move. Hit the sides of the container more often. As volume decreases pressure increases.

43 1 atm As the pressure on a gas increases 4 Liters

44 2 atm 2 Liters As the pressure on a gas increases the volume decreases Pressure and volume are inversely related

45 Temperature Raising the temperature of a gas increases the pressure if the volume is held constant. The molecules hit the walls harder. The only way to increase the temperature at constant pressure is to increase the volume.

46 300 K If you start with 1 liter of gas at 1 atm pressure and 300 K and heat it to 600 K one of 2 things happens

47 600 K 300 K Either the volume will increase to 2 liters at 1 atm

48 300 K 600 K Or the pressure will increase to 2 atm. Or someplace in between

49