Final Test (4, 12, beginning of 7)

Question 1

What is a redox rxn

Answer 1

transfer of e-

Question 2

Oxidation State Rules

Answer 2

EMFOH
E: elements: 0
Monoatomic ion: charge of ion
Fluorine: -1
Oxygen: -2 except for O22- (it is -1 in this)
Hydrogen: +1

Question 3

Steps for oxidation reduction reactions in acidic solution

Answer 3

HALF REDUCTION METHOD
1. Write separate equations
2. For each reaction
- balance all elements except H and O
-Balance O using H20
-Balance H using H ions
-Balance charges using e-
3. If necessary, multiply one or both rxns by an integer to equalize e-
4. add half rxns together, cancel identical species
5. check that elements and charges are balanced

Question 4

speed of light?

Answer 4

2.9979 *(10^8) m/s

Question 5

equation for waves?

Answer 5

wavelength*frequency = speed of light

Question 6

steps for half-rxn in basic solutions?

Answer 6

1. Use half-reaction method like acidic solutions
2. add OH- ions to counter H+ ions
3. Form H2O on side3 containing H+ and OH- and cross out duplicates on other side
4. check if elements and charges are balanced

Question 7

How are collisions and reaction rate related?

Answer 7

more collisions is a higher reaction rate

Question 8

How does concentration affect rxn rate?

Answer 8

speeds up rxn because it leads to more collisions

Question 9

how does temp affect rxn rate?

Answer 9

more temp leads to increased collisions because kinetic energy and speed

Question 10

What is activation energy?

Answer 10

min energy required to start a rxn

Question 11

What is a catalyst?

Answer 11

speeds up rxn without being consumed and lowers EA

Question 12

What is a reaction rate?

Answer 12

a change in concentration of a reactant or product per unit of time.

Question 13

what is average rate?

Answer 13

exactly what it sounds like

Question 14

what is instantaneous rate?

Answer 14

slope at a point of delta concentration over delta time

Question 15

how do equation coefficients relate to rxn rate coefficients

Answer 15

aA + bB -> cC + bB

(-1/a)(Δ A/Δ t) =
(-1/b)(Δ B/Δ t) =
(1/c)(Δ C/Δ t) =
(1/d)(Δ D/Δ t) =

Question 16

what is rate law?

Answer 16

rate = k[A]^m[B]ⁿ
k is a constant
m and n are the orders of the reactants

Question 17

what are rxn orders?

Answer 17

0: rate independent of concentration
first order: rate is directly proportional to concentration of reactant
second order: rate is proportional to square of conc.

overall reaction order: sum of individual orders

Question 18

general formula for units of K

Answer 18

M^1-n*t^-1
n is overall rxn order

Question 19

how to tell by graphs what order a rxn is?

Answer 19

0 order: ∆[A]/∆t is linear
1st order: ln(∆[A])/∆t is linear
2nd order: (1/∆[A])/∆t is linear

Question 20

Integrated rate laws:

Answer 20

zero order: [A] = -kt + [A]₀
first order: ln[A] = -kt + ln[A]₀
second order: 1/[A] = kt + 1/[A]₀

Question 21

half life formulas

Answer 21

half life =
0 order: [A]₀/2k
1st order: 0.693/k
2nd order: 1/(k*[A]₀)

Question 22

Arrhenius Equation w/ temp and activation energy

Answer 22

k= Ae^-Ea/RT
-Ea is activation energt
- A is freq factor
- R is gas constant (8.314)(J/K*mol)
- exponential factor is a # between 0 and 1 that reps the fraction of molecules that have enough energy to make it over activation barrier

Main takeaway: temperature affects rxn rate!!!

Question 23

What are rxn mechanisms

Answer 23

most chemical reactions occur through several steps, and a mechanism is a series of individual chemical steps by which an overall rxn occurs. Each step is an elementary step, which cannot be broken down further and they have to add to the overall reaction.

Question 24

what is a reaction intermediate?

Answer 24

something that is formed by a mechanism and is consumed afterwards. Not in reactants or products.

Question 25

rate laws for elementary steps and rate determining step?

Answer 25

in a series of elementary steps, there is a slow step which usually determines the overall rate of the rxn. If the first step is the slow step, the rate law only contains the reactants involved in the overall rxn. If the first step is fast and another is slow, rate law may contain intermediates. To overcome this, you have to solve for the concentration of the intermediate by assuming that an equilibrium is established in the first step.

Question 26

What is a homogenous catalyst? heterogenous?

Answer 26

Homo: all reactants and products are in same state of matter hetero: all reactants and products are in more than 1 state - for hetero, this usually entails fluids like gases adsorbing onto a solid surface.

Question 27

what does adsorbing mean?

Answer 27

the process by which a solid holds a liquid or gas onto its surface as a thin film.

Question 28

what are the steps for a heterogenous catalyst reaction?

Answer 28

1. adsorption and activation of reactants 2. migration of reactants on solid 3. reaction of adsorbed substances 4. escape (desorption) of products

Question 29

What is an acid/base catalyst?

Answer 29

acids and bases that serve as catalysts. Look at examples.

Question 30

what is Planck's constant?

Answer 30

he found that energy can only be gained or lost in whole numbers of hv! h: plancks constant (in cheat sheet). v= frequency

Question 31

What are packets of energy that occur in discrete unit size hv?

Answer 31

quantum or quanta plural. Quanta have magnitudes that depend on substance

Question 32

Who proposed that EMR is quantized? how can EMR be viewed?

Answer 32

Einstein. Streams of particles called photons

Question 33

what is the photoelectric effect?

Answer 33

metals emit e- when photons strike them.

Question 34

Properties of photoelectric effect?

Answer 34

each metal has a min frequency of light for emission to occur, and each photon has an energy proportional to that light frequency. For light w frequency lower than the threshold, no e- will be emitted regardless of intensity of light. For light w/ freq greater than threshold, e- emitted increases with intensity. For light w/ frequency greater than threshold, KE of emitted e- increases linearly w/ frequency of light.

Question 35

energy of photon equation?

Answer 35

E = hv = hc/λ

Question 36

what does e=mc² signify?

Answer 36

energy has mass, calculated using energy associated w quantity, m = E/c² with this, you can calculate mass of a photon: m = E/c², m = (hc/λ)/c², m = h/λc