CONCURRENT ENROLLMENT CHAPTER 6 CONCURRENT ENROLLMENT

HYDRATE Sodium carbonate decahydrate = Na2CO3 • 10H2O A hydrate is a compound that has a specific number of water molecules bound to its atoms. The number of water molecules associated with each formula unit of the compound is written following a dot. Sodium carbonate decahydrate = Na2CO3 • 10H2O

When heated, water molecules are released from a hydrate leaving an anhydrous compound. To determine the formula of a hydrate, find the number of moles of water associated with 1 mole of hydrate Weigh hydrate. Heat to drive off the water. Weigh the anhydrous compound. Subtract and convert the difference to moles. The ratio of moles of water to moles of anhydrous compound is the coefficient for water in the hydrate.

MATTER Solids have a definite shape and volume Liquids have a definite volume Gases will fill a container completely Compressibility The change in volume of a sample resulting from a pressure change Occurs only in gases Thermal expansion The change in volume of a sample due to a change in temperature

KINETIC THEORY Kinetic energy KE = 1/2mv2 Kinetic theory Matter is composed of tiny particles called molecules The particles are in constant motion (have kinetic energy The particles have potential energy as a result of attracting or repelling each other The average particle speed increases as the temperature increases The particles transfer energy form one to another during collisions in which no net energy is lost from the system Potential energy Energy a particle has resulting from attractive or repulsive forces

CONTINUED Cohesive force Attractive forces between two particles(potential energy) Disruptive force Force resulting from molecular motion (kinetic energy) Solid high density (particles close together), definite shape, small compressibility (particles are so close they cannot be pushed together), very small thermal expansion Liquid High density (particles close together), indefinite shape, small compressibility (particles are close, cannot be pushed together), small thermal expansion Gas Low density (particles widely separated), indefinite shape, large compressibility (mostly empty space, they can be pushed together), moderate thermal expansion

GAS LAWS Mathematical relationship that describes the behavior of gases Pressure Standard pressure 1 atm or 760 mmHg of mercury or 760 torr Learning check pg 176 Absolute zero Where all motion stops, a value of 0 on the Kelvin scale, different from Celsius by 273 Learning check pg 178

COMBINED GAS LAWS Boyle’s law Charles’s law Combined gas law Law the describes the pressure, volume, and temperature behavior of a gas at constant moles P1V1 = P2V2 T1 T2 All other laws can be found in this equation Learning check pg 182

IDEAL GAS LAW Avogadro’s law In a gas if the same volumes are at the same temperature and pressure they will have the same number of moles Standard conditions (STP) 1.00 atm and 0 oC Ideal gas law PV = nRT P = pressure (in atm); V = volume (in L); n = number of moles; R = constant, 0.0821 L.atm/mol.K; T = temperature (in Kelvin)

DALTONS AND GRAHAM’S LAW Partial pressure Total pressure exerted by a mixture of gases is equal to the sum of all the partial pressures Effusion Gas escapes through a small hole Diffusion Gases spontaneously intermingle Graham’s law Effusion rate A = (molecular mass of B)1/2 Effusion rate B (molecular mass of A)1/2

EVAPORATION AND BOILING Endothermic process of a liquid turning into a gas Condensation Exothermic process of a gas turning into a liquid Vapor pressure Molecular mass and how polar a compound is will affect the vapor pressure Smaller masses and nonpolar compounds have more vapor pressure Boiling point Temperature at which the vapor pressure of a liquid is equal to the atmospheric pressure Boiling points can be raised by increasing pressure

SUBLIMATION Sublimation Endothermic process of a solid turning into a gas Carbon dioxide or iodine solid Melting point Temperature at which a solid turns into a liquid ( the solid and liquid has the same vapor pressure) Decomposition A chemical reaction occurs due to heating Specific heat Amount of energy required to raise the temperature of 1g of substance exactly 1oC Heat = (sample mass)(specific heat)(change in temperature)

HEAT Heat of fusion Amount of energy required to melt 1g of solid at constant temp. Heat of vaporization Amount of energy required to evaporate 1g of liquid at constant temp.