Gen Chem I - Exam 2

Chapters 4, 5, 6

Oxidation

loss of electrons

Reduction

gain of electrons

Oxidation number

number representing the magnitude of change an atom would have if its shared electrons were transferred to the atom that attracts them more strongly

Redox reaction

process in which there is a net movement of electrons from one reactant to another

Oxidizing Agent

accepts electrons and decreases oxidation number

Reducing Agent

loses electrons and increases oxidation number

Activity series

list of metals in order of strength as a reducing agent; strongest on top

Atmosphere

mixture of gases that extends from a planet’s surface and eventually merges with outer space

Avogadro’s law

at constant temperature and pressure, equal volumes of any ideal gas contain equal numbers of particles; volume is proportional to moles

Barometer

device used to measure atmospheric pressure

Boyle’s law

at constant temperature and amount of gas, volume is inversely proportional to pressure

Charle’s law

at constant pressure, volume is proportional to temperature

Dalton’s law of partial pressures

in a mixture of unreacting gases, the total pressure is the sum of the partial pressures

Diffusion

movement of one fluid through another

Effusion

process by which gas escapes from its container through a tiny hole into an evacuated space

Graham’s law of effusion

rate of effusion is inversely proportional to the square root of its density or molar mass

Ideal gas law

PV=nRT

Kinetic Molecular Theory

• Particles are so small compared to the distance between them that the volume of the particles can be assumed to be negligible (zero)

• Particles are in constant straight line motion (except when they collide with container walls or each other)

• Particles have collisions that are perfectly elastic (no kinetic energy lost)

• Particles exert no forces on each other

• Average kinetic energy is directly proportional to the temperature of gas

Manometer

device used to measure the pressure of a gas in a lab

Mean free path

average distance a particle travels between collisions at a given temperature and pressure

Pascal (Pa)

SI unit of pressure

Pressure

force exerted per unit of surface area

Rms speed

speed of a molecule having the average kinetic energy

Standard atmosphere

atm; average atmospheric pressure measured at sea level and 0 degrees celsius

Standard molar volume

22.4141 L

Calorimeter

device used to measure the heat released or absorbed by a physical or chemical process taking place within it

Endothermic process

process that occurs with an absorption of heat from the surroundings; positive enthalpy change

Enthalpy

thermodynamic quantity that is equal to the system’s internal energy plus the product of the pressure and volume

Exothermic process

process that occurs with a release of heat to the surroundings; negative enthalpy change

Heat(q)

aka thermal energy; energy transferred between objects because of a difference in their temperature only

Hess’s law

enthalpy change of an overall process is the sum of the enthalpy changes of the individual steps

Internal energy

sum of kinetic and potential energies of all the particles in a system

Law of conservation of energy

total energy of the universe is constant

Molar heat capacity

quantity of heat required to change the temperature of 1 mol of a substance by 1K

Pressure volume work

type of mechanical work done when a volume change occurs against external pressure

Specific heat capacity

quantity of heat required to change the temperature of 1 gram of a substance or material by 1 K

State function

property of a system determined only by the system’s current state, regardless of how it arrived at that state

Surroundings

all parts of the universe than the system being considered

System

defined part of universe under study

Thermochemistry

study of cheat involved in chemical and physical change

Thermodynamics

study of energy and its transformations

Work

energy transferred when an object is moved by a force

Sink of energy

part of system that receives energy

Bomb Calorimeter

used to study combustion reactions in a closed rigid container because it has constant volume

Heat added to the system

+q and endothermic

Heat released by system

-q and exothermic

Work done on system

+w and compression

Work done by system

-w and expansion

Open system

exchanges matter and energy (eg. open beaker)

Closed system

exchanges energy but not matter (eg. sealed container)

Isolated system

no exchange of matter or energy (eg. thermos)