chem 1314 exam 3

gas pressure relationship

the lower the pressure the less atoms. the higher the pressure the more atoms.

pressure formula

force/area

1 atm to Pa

101,325 Pa

1 atm to psi

14.7 psi

1 atm to torr and mmHg

760 torr and mmHg

boyles law equation

P1V1=P2V2

charles law

V1/T1=V2/T2

Avogrado's Law

V1/n1 = V2/n2

ideal gas law

PV=nRT

Gay lussacs law

P1/T1=P2/T2

molar volume at STP

1 mol = 22.4 L

density of a gas at STP

molar mass/22.4 L(molar volume)

molar density of a gas

P x molar mass / R x T

Dalton's Law of Partial Pressure Equation

Ptotal=P1+P2+P3...

P1/Pt= N1/Nt

at what conditions is the ideal gas law valid?

low pressure and high temperature

kinetic molecular theory

1. gases have a definite mass but no definite volume

2. they don't have intramolecular attraction or repulsion

3. they have continuous random motion

4. the collision between gas particles are elastic

5. average KE is the same for all gases at a given temp

root mean square velocity

the square root of 3RT/m

diffusion

movement of gas atoms/molecules from area of high concentration to an area of low concentration

effusion

when gas atoms/molecules escape through a small hole into a vacuum. rate of effusion is inversely proportional to the rms velocity

grahams law of effusion

lighter atoms or molecules have faster speed

rate A/ rate B= square root of molar mass of B/ molar mass of A

real gases

there is attraction between the gas molecules and volume for each gas particle.

van der waals equation for real gases at high P and low T

(P+a n/v ^2)(V-nb)=nRT

thermochemistry

the relationship between a chemical reaction and heat/energy

system

an object or chemical reaction under study

surroundings

environment around the system

law of conservation of energy

energy cannot be created or destroyed but an be transferred from one form to another

2 types of energy

kinetic and potential

kinetic energy

energy due to motion

ex- electric, thermal

potential energy

energy due to position

ex- chemical, nuclear

calorie to joules

4.184 joules

Calorie or kilocalorie to joules

1 Cal=1000cal=4184 J

kilowatt-hour to joules

3.60 x 10 ^ 6 J

first law of thermodynamics

conservation of energy- total energy of the universe is constant- energy cannot be created or destroyed

internal energy

internal energy of a system is the kinetic energy + the potential energy of all of the particles that compose a system

state function

only depends on the initial and final values not how you get there

If change in E is negative..

the system is giving energy to the surroundings

if change in E is positive..

system is gaining energy from surroundings

energy

the ability to do work.

work + heat

q is positive if..

system gains Energy

q is negative if..

system loses Energy

if work is negative..

the work is done by the system

if work is positive..

work is done on the system

if the change in energy is positive..

energy flows into the system

if the change in energy is negative..

energy flows out of the system

heat exchange

object at high temp will decrease until thermal equilibrium is reached

quantifying heat/ heat capacity equation

q= C x change in T

specific heat capacity

amount of heat necessary to raise the temp of 1 gram of a substance by 1 degrees C.

= q/change in T x mass

molar heat capacity

amount of heat needed to raise the temp of 1 mole by 1 degrees celcius

thermal energy transfer

= q + Cs + change in temperature

pressure volume work

w= pressure x change in volume

constant-volume calorimetry

q cal = C cal x change in T

enthalpy / heat of a reaction

= E + PV

if change in H is negative..

exothermic reaction- system is releasing heat to the surroundings

if change in H is positive..

endothermic reaction- system is taking heat from the surroundings

properties of enthalpy

state function

extensive property- depends on the quantity of matter

hess's law rules

1. if reaction is multiplied by a factor then the heat of the reaction is multiplied by the same factor

2. if a reaction is reversed the sign of H is also reversed

3. the final H of the reaction is the sum of all of the steps