Mcat General Chemistry Lecture 2

Front 1

gases form a homogeneous mixture when...

Back 1

weight is similar (will settle otherwise, if temp low enough). Polarity doesn't matter.

Front 2

Characteristics of ideal gas not shared by real gas

Back 2

1) zero volume
2) exert no forces other than repulsive forces due to collisions
3) make completely elastic collisions
4) average KE directly proportional to temperature

Front 3

equation for partial pressure

Back 3

Pa=XaPtotal

Front 4

equation for Kinetic Energy

Back 4

KEaverage=3/2RT

Front 5

What is same, different, about different gases?

Back 5

Kinetic energy same, velocity different

Front 6

Graham's law equation

Back 6

v1/v2=sqrtm2/sqrtm1

Front 7

graham's law

Back 7

light gases effuse, diffuse faster

Front 8

effusion

Back 8

the spreading of a gas from high pressure to low pressure through a pinhole

Front 9

diffusion

Back 9

the spreading of one gas into another gas or into empty space

Front 10

Real gases deviate from ideal behavior when...

Back 10

Molecules are close together (Volume decreases). High pressure, low temperature.

Front 11

strength of intermolecular attractions, volume occupied by a mole of gas increase with...

Back 11

molecular mass and molecular complexity of a gas.

Front 12

Compare volume of a real gas to volume of an ideal gas

Back 12

Vreal > Videal

Front 13

Compare pressure of a real gas to pressure of an ideal gas

Back 13

Preal < Pideal

Front 14

Kinetics

Back 14

deals w/ rate of a reaction as it moves toward equilibrium.

Front 15

Thermodynamics

Back 15

deals w/ balance of reactants and products after they have achieved equilibrium

Front 16

Requirements for a collision to create new molecules in a reaction

Back 16

1) Kinetic energies of molecules must reach activation energy
2) Colliding molecules must have proper spacial orientation

Front 17

the rate of a reaction increases with what and why?

Back 17

Temperature, because more collisions w/ activation energy reached occur each second

Front 18

Factors affecting the rate of a reaction

Back 18

temperature, pressure, concentration of certain substances.
Pressure effects are usually small enough to be ignored, hvr.

Front 19

elementary reaction

Back 19

a reaction that occurs in a single step

Front 20

molecularity

Back 20

The number of molecules colliding at one time to make a reaction.

Front 21

intermediates

Back 21

species that are products of one reaction and reactants of a later reaction. Concentration often very low because often unstable and react quickly.

Front 22

factors affecting the rate of a reaction

Back 22

temperature, pressure, concentration

Front 23

units on the rate constant

Back 23

M^(1-order)/s

Front 24

for a zeroth order reaction, plotting what results in a straight line?

Back 24

[A]

Front 25

for a first order reaction, plotting what results in a straight line?

Back 25

ln[A]. Constant half life independent of concentration.

Front 26

for a second order reaction, plotting what results in a straight line?

Back 26

1/[A]. Each consecutive half life twice as long as the last. Half life dependent on concentration.

Front 27

for a third order reaction, plotting what results in a straight line?

Back 27

1/2[A]^2

Front 28

Rate determining step

Back 28

The rate of the slowest elementary step. Determines the rate of the overall reaction.

Front 29

steady state approximation

Back 29

concentration of the intermediate considered to be small and hardly changing. Leads to same result as equilibrium approximation.

Front 30

catalyst

Back 30

a substance that increases the rate of a reaction without being consumed or permanently altered. Lower activation energy or increase steric factor (p). Must increase rate of both forward and reverse reaction.

Front 31

heterogeneous catalyst

Back 31

in a different phase than the reactants and products.

Front 32

adsorption

Back 32

the binding of molecules to a surface

Front 33

absorption

Back 33

the uptake of molecules into an interior

Front 34

Why do molecules bind to a metal surface rather than to the interior?

Back 34

Metal atoms at the surface have unfulfilled valence requirements

Front 35

What does the rate of catalysis depend on?

Back 35

the strength of the bond btwn the reactant and the catalyst. If bonds too weak, not enough adsorption occurs. If too strong, too much energy required to remove the reactant.

Front 36

Reaction rates can be enhanced by doing what?

Back 36

increasing the surface area of a catalyst

Front 37

homogeneous catalyst

Back 37

in the same phase as the reactants and products

Front 38

autocatalysis

Back 38

occurs when a reaction generates the catalyst as a product

Front 39

enzymes

Back 39

a protein catalyst. Organic.

Front 40

turnover number

Back 40

the number of reactions occurring at one active site on one enzyme.

Front 41

the rate constant in a liquid is a function of...

Back 41

the solvent and the temperature

Front 42

cage effect

Back 42

reactants in a liquid can be trapped in a cage of solvent molecules, preventing them from reacting. As a result, collisions in a liquid occur at the same rate as in a gas.

Front 43

chemical equilibrium

Back 43

occurs when the forward reaction rate equals the reverse reaction rate. No change in the concentration of the products or reactants.

Front 44

the equilibrium constant depends on...

Back 44

temperature

Front 45

principle for detailed balance

Back 45

at equilibrium, the forward and reverse reaction rates must be equal. Any two or more single reactions or series of reactions resulting in the same products from identical reactants must have the same equilibrium constant.

Front 46

reaction quotient equation

Back 46

Q=coefficients of products/coefficients of reactants

Front 47

Q=K

Back 47

reaction at equilibrium

Front 48

Q>K

Back 48

reverse reaction rate greater than the forward rate. Leftward shift.

Front 49

Q<K

Back 49

forward reaction rate greater than reverse rate. Rightward shift.