CHAPTER 6 CONCURRENT ENROLLMENT

MATTER  Solids have a definite shape  Liquids will have the shape of the container, it will not always fill the container  Gases will have the shape of the container, it will always fill the container  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 –The energy a particle has when it is in motion –KE = 1/2mv 2  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 –The energy a particle has when it is at rest

CONTINUED  Cohesive force – Attractive force between particles  Disruptive force –Force resulting from particle motion  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 –How often the gas particles hit the wall and each other –Force per unit area of surface, measured in atmospheric pressure  Standard pressure –1 atm or 760 mmHg of mercury or 760 torr  Absolute zero –Where all motion stops, a value of 0 on the Kelvin scale, different from Celsius by 273

COMBINED GAS LAWS  Boyle’s law –Law that describes the pressure and volume behavior of a gas at constant temperature  Charles’s law –Law that describes the temperature and volume behavior of a gas at constant pressure  Combined gas law –Law the describes the pressure, volume, and temperature behavior of a gas at constant moles –P 1 V 1 = P 2 V 2 T 1 T 2 T 1 T 2 –All other laws can be found in this equation

IDEAL GAS LAW  Avogadro’s law –Equal volumes of gases measured at the same temperature and pressure contain equal numbers of molecules  Standard conditions (STP) –1.00 atm and 0 o C  Ideal gas law –PV = nRT –P = pressure (in atm); V = volume (in L); n = number of moles; R = constant, 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 –A process in which a gas escapes form a container through a small hole  Diffusion –A process that causes gases to spontaneously intermingle when they are brought together  Graham’s law –Effusion rate A = (molecular mass of B) 1/2 Effusion rate B (molecular mass of A) 1/2 Effusion rate B (molecular mass of A) 1/2

EVAPORATION AND BOILING  Evaporation –Endothermic process to change a liquid into a gas  Condensation –Exothermic process in which a gas changes into a liquid  Vapor pressure –Pressure exerted by vapor that is in equilibrium with its liquid –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  Endothermic process where a solid converts to a gas without going through the liquid phase  Carbon dioxide or iodine solid  Melting point –Temperature at which a solid changes to a liquid; the solid and liquid have the same vapor pressure  Decomposition –Change in the chemical properties resulting from being heated  Specific heat –Amount of energy required to raise the temperature of 1g of substance exactly 1 o C –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.