1. Active Chemistry Kinetic Molecular Theory and the Gas Laws

2. Phases of Matter There are four phases of matter: 1. Solid 2. Liquid 3. Gas 4. Plasma The state of matter depends on the motion of the molecules that make it up.

3. Solids Solids are objects that have definite shapes and volumes. The atoms or molecules are tightly packed, so the solid keeps its shape. The arrangement of particles in a solid are in a regular, repeating pattern called a crystal. Microscopic picture of a solid.

4. Liquids The particles in a liquid are close together, but are able to move around more freely than in a solid. Liquids have no definite shape and take on the shape of the container that they are in. Microscopic picture of a liquid.

5. Gases A gas does not have a definite shape or volume. The particles of a gas have much more energy than either solids or liquids and can move around freely. Microscopic picture of a gas.

6. Plasma Plasma is a gas-like mixture of positively and negatively charged particles. It is found in stars, such as the sun, and in fluorescent lighting. Plasma occurs when temperatures are high enough to cause particles to collide violently and be ripped apart into charged particles.

7. Postulates of KMT A gas consists of a collection of small particles traveling in straight-line motion. The molecules in a gas occupy no volume (that is, they are points spread far apart). Collisions between molecules are perfectly elastic (that is, no energy is gained or lost during the collision). There are no attractive or repulsive forces between the molecules. The average kinetic energy of a molecule is proportional to the Temperature. Molecules can collide with each other and with the walls of the container. Collisions with the walls account for the pressure of the gas.

8. At the same temperature, lighter gases move faster than heavier gases.

9. Temperature Temperature is a measure of the amount of the average kinetic energy of the particles in matter. The more kinetic energy the particles have, the higher the temperature. The temperature of particles are usually recorded in one of three ways: 1. Fahrenheit (ºF) 2. Celsius (ºC) 3. Kelvin (K) **SI unit!!!

10. Fahrenheit Developed by Daniel Gabriel Fahrenheit, who is best known for inventing the alcohol thermometer and mercury thermometer in the early 1700’s. It is based on 32º for the freezing point of water and 212º for the boiling point of water. The interval between the freezing and boiling points are divided into 180 parts. The conversion to Fahrenheit is: ºF = (9/5ºC) + 32

11. Celsius Scale developed by Anders Celsius in the early to mid-1700’s, working from the invention of Fahrenheit's thermometers. The Celsius scale is based on 0º for the freezing point of water and 100º as the boiling point. The interval between the freezing and boiling points are divided into 100 parts. The conversion to Celsius is: º C= (5/9)( º F-32) º C= (5/9)( º F-32) º C= K-273 º C= K-273

12. Kelvin Developed by William Thompson Kelvin in 1848, Kelvin is a temperature scale having an absolute zero below which temperatures do not exist. At 0K, all molecules cease any type of motion (as in the temperature of outer space). It corresponds to a temperature of -273°C. The Kelvin degree is the same size as the Celsius degree, so the freezing point of water is at 273K and the boiling point is at 373K. The conversion to Kelvin is: K= º C +273

14. Temperature Conversions Ex. 1: The boiling point of Liquid Nitrogen is –195 0 C, what is the temperature in Kelvin? Formula: K = 0 C + 273 K = -195 + 273 = 78.0 K (3 Sig Dig)

15. Temperature Conversions Ex. 2 The normal body temperature is 310. K, what is it in Celsius? Formula: 0 C = K - 273 0 C = 310. – 273 = 37.0 0 C

16. Temperature and Volume Click here for Demonstration

17. Volume and Temperature Pressure and the # of particles are constant then As Temperature decreases, Volume _________ or or As Temperature increases, Volume __________ This is a relationship direct decreases increases

18. Charles’ Law Example A quantity of gas occupies a volume of 506 cm 3 at a temperature of 147 o C. Assuming that the pressure remains constant, at what temperature will the volume of the gas be 604 cm 3 ? V 1 = 506cm 3 V 2 = 604cm 3 T 1 = 147 o C + 273 =420KT 2 = ??

19. A Graph of Charles’s Law

20. Charles Law If n (moles) and P are constant, then V α T V and T are directly proportional. If one temperature goes up, the volume goes up! V 1 V 2 T 1 T 2 = Jacques Charles (1746-1823) (1746-1823)

21. Charles’ Law Doubling the Kelvin temperature of a gas makes the gas expand resulting in doubling the volume of the gas