# Gen chem

Extensive property

- Independent of size of system
- mass, force, volume, moles, are, length
HINT - change depending on the EXTENT to which the size changes

Intensive property

Independent of size. Includes temperature, pressure, density. A baby and a 7 foot tall basketball player wall have the same temperature - independent of size.

State function

Intensive/extensive properties. Path independent. Includes mass and temperature. Depends only on the current state of system. Eraser created 5 different ways in different factories but created the same eraser. Therefore independent of path

Two ways that energy transfer occurs

1. heat
2. work

Three ways transfer of energy via heat occurs

1. conduction - energy transfer due to contact (holding a pen for a minute raises the temp of the pen)
2. convection - energy transfer due to movement of fluid
3. radiation - occurs via electromagnetic waves

Work in chemistry

Chemical system that is stationary can still do work by expansion

Chemistry work equation

pressure time change in volume

Equation for pressure

force divided by area (F/A)

Second law of thermodynamics

Heat cannot be converted completely to work. The entropy of an isolated system will always either be maintained or increase
e=1-Tc/Th

Internal energy

the collective energy of all molecules found in the system

Kinetic energy types

translational - velocity
vibrational - attractive/repulsive
rotational - torque

Potential energy types

Electrostatic
intermolecular
rest mass (e=mc^2)
state function

enthalpy is a ___ fucntion

state - the pathway taken to get to final product will not effect enthalpy

entropy

the tendency of a system to take its most probable form. AKA natures way of spreading energy evenly through a system

entropy of universe is equal to

entropy of system plus entropy of surroundings. entropy of universe must always be greater than 0 due to second law of thermodynamics

entropy is a ___ property

extensive and state

enthalpy tells us what about a reaction?

if it is endothermic or exothermic, not if it is spontaneous

entropy of a reaction determines ___

spontaneity

Gibbs free energy
1) 0
2) negative
3) positive

1. equilibrium
2. negative = spontaneous
3. positive = non-spontaneous

heat capacity

the amount of energy required to change an object's temperature by some amount

heat capacity is a ___ property

extensive

Two types of heat capacity

1. Specific - mass
2. Molar - moles

bomb calorimeter

measures the change in energy of a reaction when at least one of the reactants is a gas. volume is kept constant, so no expansion will occur.

coffee cup calorimeter

reactants are liquid and solids. these are kept at constant pressure

condensation

gas molecules lose kinetic energy and get stuck in the liquid. occurs at the surface

evaporation

liquid molecules increase in kinetic energy and escape from liquid to gas form. occurs at the surface

boiling point

the temperature at which the molecules in liquid gain enough kinetic energy to escape into gas form. The vapor pressure created by liquid is equal to or greater than the total pressure found above in the atmosphere.

phase change states

1. melting
2. freezing
3. vaporization
4. condensation

melting

energy required - endothermic --> intermolecular bonds broken leading to increase in potential energy. positive enthalpy of fusion

freezing

energy released - exothermic. negative enthalpy of fusion

vaporization

requires energy - endothermic intermolecular bonds broken leading to increase in potential energy. positive enthalpy of fusion

condensation

energy released - exothermic. negative enthalpy of fusion

colligative properties

depend solely on the concentration of the solute added
1. vapor pressure
2. osmotic pressure
3. boiling point
4.

vapor pressure

pressure due to gas molecules when they are in dynamic equilibrium with liquid molecules

Adding nonvolatile solute - one that will not evaporate - causes a ____ in vapor pressure, while adding volatile solute ____ vapor pressure.

decreases, increases

boiling point has what relation with vapor pressure?

inversely. adding a nonvolatile solute lowers vapor pressure. now a higher temperature is required to raise vapor pressure to atmospheric pressure

adding solute has what effect on freezing and melting points?

both points are lowered

osmotic pressure

the tendency of water or another solvent to flow to an area of higher solute concentration

vont hoff factor

the amount of particles a reactant breaks into

ion pairing

the momentary aggregation of electrically charged ions in a concentrated solution of two or more compounds. does not exist in ideal solutions. in ideal solutions, all ions are separated from each other by solvent molecules

barometer

used to measure pressure. requires
1. long, cylindrical tube at one end
2. a dense liquid usually mercury
3. a cup filled with the liquid

ideal dilute solutions

every solute molecule is separated from one another

solute

compound of which there is less

solvent

compound of which there is more

which conducts electricity better: water or an aqueous solution

an aqueous solution

colloids

mixture of two or more compounds found in different states. similar to solution but with solutions they are in the same state

colloidal particle

the larger particles of colloids

examples of colloids

blood - water and hemoglobin
fog = liquid and gas
smoke = solid and gas
whipped cream = gas and liquid
paint = liquid and solid

tyndall effect

the scattering of light due to large particles

solvent portion of colloid is known as ___ and the solute portion of colloid is known as ____

solvent = continuous phase
solute = dispersed phase

lyophilic vs lyophobic colloids

lyophilic = strong attraction between continuous phase and dispersed phase colloids
lyophobic = no attraction between continuous phase and dispersed phase colloids

how to filter colloids

heat --> coagulation --> filtration
dialysis = separation via semi-permeable membrane

molarity

moles of solute / volumes of solution

intermolecular bonds

non-covalent bonds that hold 2 or more molecules together

non-ideal fluid

1. volume of molecules cannot be neglected
2. intermolecular forces exist

Solubility reaction. Forward reaction = ___ and reverse reaction = ____.

Forward = dissolution
Reverse = precipitation

Solubility constant accounts for what?

not solids/liquid

Arrheneous base/acid

base = compound that produces H+ ions in water
acid = substance that produce OH- ions in water

In aqueous solution, ___ is responsible for acidic properties and ____ is responsible for basic properties

acidic = H3O+
basic = OH-

example of problem with Arrheneous base/acid definition

NH3 is basic, but does not contain OH-, so cannot be considered a base

The most basic definition of acid/base

Lewis

Lewis acid/base

acid = anything that accepts an electron pair to form a new bond
base = anything donates an electron pair to form a new bond

autoionization

the dissolution of 2 water molecules

Ka values and correlation to strong/weak acid

Ka > 1 = strong acid
Ka < 1 = weak acid

Kb values and correlation to strong/weak acid

Kb > 1 = strong base
Kb < 1 = weak base

strong bases react with weak acid to produce what type of salt

basic salts

strong bases react with strong acid to produce what type of salt

neutral salts

weak bases react with strong acid to produce what type of salt

acidic salts

weak acids and weak bases react to produce what type of salt?

there is a competition and the Ka and Kb values must be considered

titration

the process of adding an acid to a base or a base to an acid with the purpose of determining concentration of our unknown acid or base

buffer

a chemical system that resists pH changes

oxidation state of oxygen

-2

oxidation state of oxygen in elemental state

zero. the oxidation state of any element in elemental state is zero

electrochemical cells

a way to capture he useful work produced by the movement of electrons

electrode

metals that conduct electrical current into/out of solution

anode

the half cell where oxidation takes place

cathode

the half cell where reduction takes

in voltaic cells, how do electrons flow?

from the lower electric potential (anode) to the higher electric potential (cathode). this is due to the fact that electrons have a negative charge.

in voltaic cells, positive charge and current flows how?

from cathode (high potential) to anode (low potential)

electrochemical cell AKA

battery

Coulomb is a way of measuring what?

the amount of electrons transferred from point A to point B. 1 Coulomb = 6.24 x 10^12 electrons

96500 C/mol of electrons - rounded

relationship between concentration and electrical gradient values

they are opposite each other.