States of Matter Chapter 3

Kinetic Molecular Theory Tries to explain the behavior of matter States that: All matter is made of small particles (atoms, molecules and ions) These particles are in constant, random motion These particles collide with each other and the walls of their container When these collisions happen, they do not lose energy

Types of Energy Thermal energy The total energy of the particles Includes energy from vibrations and the energy that holds the particles in place

Types of Energy Kinetic Energy How fast the particles are moving Scientists measure this as temperature

States of Matter and their Properties

Solids Particles are tightly packed Have a regular, orderly arrangement Particles do not move but vibrate in place Solids have both definite shape and volume

Liquids These particles have gained enough kinetic energy to slide past each other = flow How easily a liquid flows = viscosity The particles have more kinetic energy than in the solid state

Liquids The temperature at which a substance changes from a solid to a liquid is called the melting point Liquids can expand as the temperature increases Ex. Thermometer Liquids have no definite shape but a definite volume

Gases These particles have enough energy to move freely These particles have more kinetic energy than in the liquid state The temperature at which a substance changes from a liquid to a gas is called the boiling point

Gases Gases undergo diffusion = even spreading of particles in the container they are in, the particles will move around as needed on their own to achieve this and then continue to move and collide Gases also expand as the temperature increases Ex. Hot air balloon

Gases No definite volume or shape

Pressure Gases exert pressure = force of the collisions of gas particles with anything in their path (often the walls of the container that they are in) The more collisions, the higher the pressure Unit = pascal

Pressure & Volume What happens to the pressure if I decrease the volume of the container? P1V1P1V1 P2V2P2V2 1 = initial conditions 2 = final conditions When volume decreases, pressure increases because there is less room in the container, and the particles hit the sides more often. Think of pressure as collisions. The more collisions, the greater the pressure

Pressure & Volume This relationship between pressure and volume is called Boyle’s Law Boyle’s Law Equation = V 1 x P 1 = V 2 x P 2

Practice The pressure of an 18.0 mL sample of gas changes from 4.0 Pa to 8.0 Pa at a constant temperature. What is the new volume? V 1 = 18.0 mL P 1 = 4.0 Pa V 2 = ? P 2 = 8.0 Pa What formula will we use? V 1 x P 1 = V 2 x P 2 Before we solve, think – if we doubled the pressure, what would happen to the volume?

Practice 18.0 ml x 4.0 Pa = X x 8.0 Pa 72ml*Pa = 8.0 Pa*X 8.0 Pa 9.0 ml = X Volume was cut in half

Temperature & Volume What happens to the volume if I decrease the temperature of the container? T1V1T1V1 T2V2T2V2 When temperature decreases, volume decreases because particles need less room as they move slower to keep the number of collisions (pressure) constant. Decreased temperature makes particles move slower

Temperature & Volume This relationship between temperature and volume is called Charles’s Law Charles’s Law equation = V 1 = V 2 T 1 T 2 Temperature must be in Kelvin!

Practice A gas sample has a volume of 100 mL at 200 K. The temperature of the sample is increased to 400 K. What is the new volume of the gas? V 1 = mL T 1 = 200 K V 2 = ? T 2 = 400 K What formula will we use? V 1 = V 2 T 1 T 2 Before we solve, think – if we doubled the temperature, what would happen to the volume?

Practice 100 mL 200 K 40,000 mL*K = 200 K*X 200 K 200 mL = X Volume was doubled = X 400 K