Chem 400 Exam 2

Front 1

Gas

Back 1

Consists of well-separated particles (atoms, ions, or molecules) in constant random motion.

Front 2

Kinetic Energy of Gas Particles

Back 2

KE=(1/2)mv^2

Front 3

Cooling Down Gases through Collisions

Back 3

Don't cool down due to particle collisions. Can cool down due to collisions with the walls of their containers, if the walls collide with cooler particles outside the container.

Front 4

Effusion

Back 4

A special case of diffusion in which gas particles diffuse through a tiny hole.

Front 5

Rate of Effusion

Back 5

How rapidly the gas particles escape through the hole.

Front 6

Graham's Law

Back 6

((Rate of effusion A)/(rate of effusion B))=((vГMm of B)/vГMm of A))

Front 7

Gas Pressure in a Sealed Container

Back 7

The result of constant moving particles striking the inside surface (wall) of the vessel.

Front 8

760 torr

Back 8

1 atm

Front 9

760 mmHg

Back 9

1 atm

Front 10

Ideal Gas

Back 10

Particles have mass but no volume. There are no forces of attraction or repulsion.

Front 11

Ideal Gas Law

Back 11

PV=nRT

n - number of moles of gas

Front 12

Combined Gas Law

Back 12

((P1V1)/(n1T1))=((P2V2)/(n2T2))

Must use kelvin

Front 13

Molar Volume of a Gas

Back 13

The volume occupied by 1 mole of the gas.

Front 14

Molar Volume at STP

Back 14

22.4L

Front 15

STP

Back 15

0°C 1atm

Front 16

Density of Gas at STP

Back 16

((Mass of 1 mole)/(volume of 1 mole)) = ((molar mass)/(22.4L))

Front 17

Mole Fraction of a Gas

Back 17

Xa = (na/ntotal)

Front 18

Partial Pressure

Back 18

Pa = Xa × Ptotal

Front 19

Pressure of Collected Gas

Back 19

Pgas = Pmeasured - Pwater vapor

Front 20

Avagadro's Law

Back 20

Doubling the moles doubles the volume for any gas (if P and T remain fixed).

As a result, the molar ratio in an equation is also the gas volume ratio.

Front 21

Real Gases

Back 21

Particles have volume. Particles weakly attact eachother.

Front 22

Real Gas Volume

Back 22

More than idea had volume.

VR = VI + nb

n-moles

b-particle size

Front 23

Real Gas Pressure

Back 23

Less than ideal gas pressure.

PI = PR + ((n^2×a)/(VR^2))

Front 24

Forms of Energy

Back 24

Electrical, chemical, heat, nuclear, light, electrostatic, kinetic (movement), and potential (stored).

Front 25

System

Back 25

The part of the universe we are interested in.

Front 26

Surroundings

Back 26

Everything else in the universe that is not the system.

Front 27

Exothermic Process

Back 27

Heat energy leaves the system.

Front 28

Endothermic Process

Back 28

Heart energy enters the system.

Front 29

Internal Energy

Back 29

The energy stored in a 'chunk' of matter.

Includes KE if particles, bond energy, electron energy, and nuclear energy.

Front 30

Kinetic Energy

Back 30

If the 'chunk' of matter is moving.

Front 31

Potential Energy

Back 31

Given from having distance from the center of the Earth.

Front 32

Total Energy

Back 32

Etotal = Ek + Ep + U

Front 33

U

Back 33

Internal energy

Front 34

Change in Internal Energy from a Reaction

Back 34

^U = Uproducts - Ureactants

Front 35

q

Back 35

Heart energy

Front 36

w

Back 36

Work energy

Front 37

Total Energy Produced

Back 37

^U = q + w

Front 38

cal

Back 38

4.184 J

Front 39

Enthalpy

Back 39

H

Front 40

Enthalpy Change

Back 40

^H

q when expressed 'per mole', 'per reaction', or ' per gram'

Front 41

^H

Back 41

^H=H products-H reactants

Front 42

Thermochemical Equation

Back 42

A balanced equation showing the enthalpy change for the reaction, ^Hrxn

Front 43

Heat (Enthalpy) of Combustion, ^Hcomb

Back 43

^H when 1 mole of a substance is burned in O2.

Note: the coefficient of the convicted substance must be 1, so fractional coefficients may be necessary.

Front 44

Heat (Enthalpy) of Formation, ^Hf

Back 44

Enthalpy change when 1 mole of a compound is formed from its elements.

Front 45

Heat Capacity

Back 45

The energy needed to raise a 'chunk' of materials temperature by 1°C (J/°C)

Front 46

C

Back 46

Heat capacity

Molar heat capacity

Front 47

Heat Capacity Equation

Back 47

q=C^T

Front 48

Specific Heat Capacity

Back 48

The energy needed to raise a 1 gram sample of a materials temperature by 1°C (J/g/°C)

Front 49

c

Back 49

Specific Heat Capacity

Front 50

Specific Heat Capacity Equation

Back 50

q=mc^T

Front 51

Molar Heat Capacity

Back 51

The energy needed to raise the temperature of a 1 mole sample of a materials by 1°C (J/mol/°C)

Front 52

Molar Heat Capacity Equation

Back 52

q=nC^T

Front 53

q of metal in calorimeter

Back 53

qmetal=-(qwater+qCal)

Front 54

Heat (Enthalpy) of Fusion, ^Hfus

Back 54

The energy required to melt 1 mole (or 1 g) of a substance.

Front 55

Heat (Enthalpy) of Vaporization, ^Hvap

Back 55

The energy required to vaporize 1 mole (or 1 g) of a substance.

Front 56

^Hfus/^Hvap

Back 56

q=m^Hfus

+ for melting/vaporizing

- for freezing/condensation

Front 57

Standard State

Back 57

The physical state (s,l,g) of the element at standard condition (25°C, 1 atm, 1 Molar solution)

Front 58

Reference Form

Back 58

Specifies the most stable (lowest energy) allotrope for elements with multiple forms.

Front 59

Reference Form for Sulfur

Back 59

Rhombic

Front 60

Reference Form for Carbon

Back 60

Graphite