Mean (Average) The mean is the total of all of the values divided by the number of values Example: Find the mean of 2, 3, 7, 7, 4 Step 1: 2 + 3 + 7 + 7 + 4 = 23 Step 2: There are 5 numbers added together Step 3: Divide the total of the values (23) by the number of values (5) Answer: 23 / 5 = 4.6

Pressure The force applied over a specific area. Common Units: Pounds per square inch (psi) Atmosphere (atm) Torr (torr) Pascal (Pa) Conversions: 1 atm = 14.6956 psi = 760 torr = 101325 Pa

Volume The amount of space a sample of matter occupies. A cube with sides of 10 cm has a volume of: 10 cm x 10 cm x 10 cm = 1000 cm3 = 1000 mL = 1 L 1 cm3 = 1 mL Volume is often calculated using the water displacement method.

Temperature A measure of the average kinetic energy of the atoms and molecules in a sample of matter. Common Units and Conversions: Degrees Fahrenheit (°F) °F = (9/5)°C + 32 Degrees Celsius (°C) °C = (5/9)(°F -32) Kelvin (K) K = °C + 273

Avogadro’s Law n = kV V1 n1 V2 n2 = When temperature and pressure are held constant, the number of molecules (n) is equal to a constant (k) times the volume (V); therefore, V1 n1 V2 n2 =

Charles’ Law V = kT When pressure is held constant, volume (V) is equal to a constant (k) times the temperature (T); therefore, V1 V2 T1 T2 =

Boyle’s Law PV = k When temperature is held constant, pressure (P) times volume (V) is equal to a constant (k); therefore, P1V1 = P2V2

Gay-Lussac’s Law P = kT P1 P2 T1 T2 When volume is held constant, pressure (P) is equal to a constant (k) times the temperature (T); therefore, P1 P2 T1 T2 =

Proportional Relationship A mathematically predictable relationship where one variable increases, another increases. Example: Boyle’s Law (PV = k) P ↑ V ↓ P ↓ T ↑

Inversely Proportional Relationship A mathematically predictable relationship where one variable increases, another decreases. Examples: Charles’ Law (V = kT) V ↑ T ↑ V ↓ T ↓ Gay-Lussac’s Law (P = kT) P ↑ T ↑ P ↓ T ↓