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CHM 142 +145 > CHM 142 exam 4 > Flashcards

CHM 142 exam 4 Flashcards

1
Q

the study of electricity and chemical reactions

A

electrochemistry

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2
Q

half- reactions

A

equations that only show oxidation or reduction alone

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3
Q

electrons are shown as— in oxidation

A

products

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4
Q

electrons are shown as — in reduction

A

reactants

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5
Q

What are the steps to balancing redox reactions?

A
  1. Balance any atoms that are not O or H
  2. Balance O by adding H20
  3. Add H to balance out any H added by the H2O
  4. Balance electrons (make sure charges are equal)
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6
Q

voltaic cell

A

a device that facilitates the transfer of electrons externally by a wire instead of directly through the reactants

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7
Q

loses mass over time, negative, where oxidation occurs, anions flow to this

A

anode

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8
Q

gains mass over time, positive, where reduction occurs, cations flow to this

A

cathode

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9
Q

what is the purpose of a salt bridge in a voltaic cell?

A

to keep the solutions neutral so electrons flow from anode to cathode

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10
Q

electrons flow—from the anode to the cathode

A

spontaneously

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11
Q

the potential difference between two electrodes of a voltaic cell

A

cell potential/emf/Ecell

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12
Q

Ecell=

A

Ecathode-Eanode

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13
Q

the more — a Ecell value is the more likely it is for — to occur

A

positive, reduction

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14
Q

what are four things that affect cell potential

A
  1. the reactions that occur at the electrodes
  2. concentration of products and reactants
  3. pressures of gaseous products or reactants
  4. temperature
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15
Q

Does changing the coefficents in a rxn equation change the cell potential?

A

No

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16
Q

if the value of Ecell is negative the rxn is —

A

nonspontaneous

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17
Q

If the value of Ecell is positive what is the sign of gibbs free energy

A

negative, the rxn is spontaneous

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18
Q

Delta G=

in relation to emf

A

-nFE

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19
Q

Faradays constant

A

96485 C/mol

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20
Q

nernst equation

A

E= Estandard - (RT/nF) *ln(Q)

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21
Q

concentration cell

A

a volatic cell that is made with the same chemical species with diff concentrations in each half cell

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22
Q

portable, self containted electrical power souce with one or more volatic cell

A

battery

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23
Q

non rechargeable battery

A

primary cell

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24
Q

rechargeable battery

A

secondary cell

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25
Q

lead acid battery

A

used in cars, toxic reactants, rechargeable

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26
Q

alkaline battery

A

non rechargeable, lightweight, most popular primary battery

AA and AAA batteries

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27
Q

Ni-Cd/metal battery

A

secondary cell, found in electronics, cadmium not around anymore bc/ toxic

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28
Q

Are fuel cells batteries?

A

No, they need a constant supply of fuel to operate

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29
Q

voltaic cell that uses H2 or CH4 to turn chemical E into electrical E

A

Fuel cell

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30
Q

Corrosion

A

Spontaneous redox reaction that involved the degredation of a metal by another substance

ex: rusting

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31
Q

Examples of corrosion prevention

A
  • painting over metal (not the best option)
  • cathodic protection (ex: galvanized iron)
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32
Q

when zinc is placed over iron to protect it from rusting because zinc has a lower reduction value so it will oxidize more easily

A

galvanized iron

33
Q

non spon redox reactions driven by electrical E

A

electrolysis

34
Q

Q=

Q here equals coulombs

A

It=nF

n= number of moles of e- through the wire

35
Q

protons + neutrons =

A

mass number

36
Q

number of protons

A

atomic number

37
Q

Does the mass number go on the top or on the bottom?

A

top, atomic number goes on the bottom

38
Q

Alpha decay

A

stream of alpha particles (4/2He)

39
Q

Beta decay

A

emission of high energy electrons, increases number of protons

40
Q

gamma decay

A

emission of high energy photons, does not change neutrons or protons

41
Q

Positron emission

A

emits positron/ anti electron, opposite of beta decay bc it increases neutrons

42
Q

electron caputre

A

nucleus captures electron from electron cloud, increases neutrons

43
Q

all nuclei with more than — protons are radioactive

A

84

44
Q

if a nucleus is above the band of stability what kind of decay does it undergo?

high neutron to proton ratio

A

beta decay to increase protons and decrease neutrons

45
Q

if a nucleus is below the band of stability what kind of decay does it undergo?

low neutron to proton ratio

A

positron emission or electron caputre to increase the number of neutrons

46
Q

True or false? A nucleus with an even number of protons is more likely to be stable than one with an odd number?

A

True

47
Q

changes in the nucleus because of contact with another particule

A

Nuclear transmutations

48
Q

Radioactive deacy is a — order process

A

1st order

49
Q

first order half life

A

k = .693/ t1/2

or t1/2 = .693/k

50
Q

True or false half lives for nuclear decay are affected by external factors like Temp, pressure, state of matter, etc.

A

False half life is unaffected by these factors

51
Q

ln(Nt/N0) =

A

-kt

52
Q

the rate at which a sample decays

disentegrations per unit of time

A

activity

53
Q

1 bequerel =

A

1 disentigration per second

54
Q

1 curie =

A

3.7*10^10 disentigrations per second

55
Q

phosphors

A

substances that emit light when radioactive particles strike them

56
Q

count the number of light flashes emitted by phosphors

A

scintillian counter

57
Q

radiotracers

A

follows the path of an elements through a reaction, used to better understand reacton mechanisms

58
Q

change in E/E=

A

change in m * c^2/ m*c^2

59
Q

speed of light =

A

2.9979*10^8

60
Q

Nuclear binding Energies

A

the amount of energy necessary to seperate a nucleus into its nucleons

61
Q

fission

A

separating a heavy nucleaus into a smaller more stable one

62
Q

fusion

A

combining smaller nuclei into larger more stable ones

63
Q

if the mass of the nucleus is too large (supercritical mass) the reaction escalates into a violent explosion

A

chain reaction

64
Q

critical mass

A

the amount of fissionable material needed to maintain a constant rate of fission

65
Q

super critical mass

A

mass is too large and creates a chain reaction

too much fissionable material

66
Q

subcritical mass

A

mass is not enough and no reaction occurs but materials are still radioactive

not enough fissionable material

67
Q

fissionable material in a nuclear reactor

enriched uranium

A

fuel elements

68
Q

absorb neutrons to keep a consant rate of fission and no over heating

A

control rods

69
Q

slows down neutrons so they are more easily captured and then produce fission

A

moderator

ex: water or graphite

70
Q

carry heat away from reaction

A

primary coolant

71
Q

carries heat from primary coolant to turn turbine

A

secondary coolant

72
Q

why is fusion not used to generate nuclear power right now?

A

The conditions it requires is too extreme to happen on earth right now

really high temperature and pressures

73
Q

what kind of radiation is more harmful? Ionized or non ionized?

A

Ionized radiation is more harmful because it strips water molecules and creates harmful free radicals (OH)

alpha, beta, gamma

74
Q

the gray

measure of radiation

A

1 J of E per kg/tissue

75
Q

rad (radiation absorbed dose)

measure of radiation

A

1*10^-2 J of E per Kg/tissue

76
Q

1 Gy =

A

100 rad

77
Q

RBE (relative biological effectiveness) =

A

1 in gamm and beta = 10 for alpha

78
Q

effective dossage =

can be sieverts

A

number of rad * RBE

79
Q

1 Sv=

A

100 rem

CHM 142 +145 (6 decks)

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