Unit 4 (ch 19) Flashcards
1
Q
batteries produce energy via
A
spontaneous redox processes
2
Q
redox chemistry
A
e- gained or lost through reduction and oxidation
3
Q
oxidation
A
losing e-
4
Q
reduction
A
gaining e-
5
Q
something that is oxidized is a
A
reducing agent
6
Q
electrochemical cells
A
two physically separated half cells
7
Q
use e red values to determine
A
cell potential
8
Q
cell potential
A
measure of force pushing e+ from anode to cathode
9
Q
E cell=
A
E cathode (reduced) - E anode (oxidized)
10
Q
movement of electrons from anode to cathode produces
A
electrical work
11
Q
E cell should always be
A
positive
12
Q
delta G cell
A
welec
13
Q
welec=
A
nFEcell, moles x faraday x ecell= J
14
Q
C=
A
n x F
15
Q
faradays constant
A
9.65x10^4
16
Q
welec measures
A
energy associated with electrochemical cell
17
Q
standard hydrogen electrode cathode
A
II H+(1 M) I H2(g), 1atm I Pt
18
Q
standard hydrogen electrode anode
A
Pt I H2(g), 1atm I H+ (aq, 1 M) II
19
Q
How can delta G relate to batteries?
A
delta G = -n x F x Ecell
20
Q
non standard E cell =
A
E cell (standard) - RTlnQ/ (nF)
21
Q
as Q increases,
A
0.0592 / n log Q also does
22
Q
increase concentration =
A
increase E red
23
Q
< 1 M =
A
decreasing E cell
24
Q
> 1 M =
A
increasing E cell
25
finding k
log k = n x E cell/ (0.0592)
26
k < 1
E cell < 0 (reactants)
27
k > 1
E cell > 0 (products)
28
how to determine battery capacity
w elec = - C x E cell
29
1 ampere =
1 coulomb/second
30
1 coulomb =
1 amp x sec
31
1 C V =
1 J
32
1 J=
1 A x s x V
33
1 watt =
volts x current (J/s)
34
1 w =
1 J/s
35
1 kw=
1000 J/s
36
1 kw x hr=
1000 w x hr
37
1 watt =
1 A x V
38
Why are batteries important and why would it be good if they were improved?
- power many aspects of our lives
| - lighter, higher capacity batteries would increase the efficiency and utility of battery powered devices
39
voltaic cell
energy generated by spontaneous redox processes
40
electrolytic cell
recharging reverses the process
41
oxidation occurs at the
anode
42
reduction occurs at the
cathode
43
electrochemical reactions consist of
two half reactions which must be electrochemically balanced
44
standard potential of cell is calculated how?
- use standard reduction potentials
| - Ecell= Ecathode-Eanode
45
more positive reduction potential is
cathode
46
movement of electrons from anode to cathode (blank)
produces electrical work
47
what are the standard conditions for E not cell?
1 atm and 1 M
48
E not cell values are not dependent on (blank)
stoichiometry
49
delta G cell
- nFEcell
50
Delta G cell relates
work and free energy of the system
51
moles of electrons (n) is
number gained or lost
52
How many moles (n) does this equation have?
Cu^2+ +Zn(s)--> Zn2+ + Cu(s)
53
most of our e not cell values are relative to the
standard hydrogen electrode
54
if you are at 298 K, Ecell =
E not cell - (0.0592 log Q/ n)
55
At equilibrium, logK
n E not cell / 0.0592
56
1 C V =
1 J
57
1 J =
1 AsV
58
1 W=
1 J/s
59
1 As =
1C
60
what are the conversions of batteries used for
determine how long it takes to recharge a battery
61
What are uses of nuclear chemistry?
- energy (fusion and fission)
- climate science
- medical scanning (CT and PET)
- archaeology
- smoke detectors
- x- rays
- food preservation
- cancer treatments
62
Nuclear chemistry helps us understand
how universe began
63
describe neutron stability
not stable and decay into proton and electron
64
matter can be transformed to energy (equation)
E= mc^2
65
radioactive decay is
first order
66
what does it mean by first order?
depends only on how many radioactive ions/isotopes we have
67
radioactive decay is measured by
half life
68
half life equation
n= t/ t 1/2
69
Nt/N0=
0.5^ n or 0.5^t/t1/2
70
fusion of nuclei gives
larger nuclei, often giving off positrons or other particles in the process
71
positrons
are anti-matter and combine with electrons to annihiliate and produce a gamma ray
72
binding energy
determine mass difference between starting (proton/neutrons) and final nucleus mass, determine E
73
nucleus held together by
strong force
74
when can larger nuclei go through different decay processes
if they aren't stable
75
isotope with higher mass number
neutron rich and decay by beta decay
76
beta decay
give off electron as neutron converts to proton
77
unstable isotope lighter than stable
neutron poor, positron emission or electron capture, more neutrons
78
larger isotopes often go through
alpha decay
79
alpha decay
alpha particle (helium nucleus) lost
80
After what element are all species radioactive? Why?
Bismuth
| -repulsive forces between protons too strong
81
how to make bigger nuclei?
decay processes, smash nuclei with neutrons or other nuclei
82
how can we make gold?
smash nuclei with neutrons or other nuclei to build bigger ones
83
current nuclear energy applications rely (blank)
nuclear fission
84
describe nuclear fission
235U captures neutron, becomes 236 U, which quickly decomposes to generate other smaller nuclei and neutrons, which keep process going
85
radioactivity is measure in
curies (Ci) or becquerels (Bq)
86
rate of decay =
A= kN
87
radiometric dating takes advantage of (blank)
radioactive isotopes with known half-lives to determine age based on amount of remaining radioactivity
88
what is used to date rocks?
235 U
89
what is used to date formerly living things?
14 C
90
Why is radiation bad for living things?
has lots of energy and can form highly reactive species like hydroxyl radicals with can react with proteins and DNA
91
Ionizing radiation/mass is measured in
Grays (Gy)
92
1 Gy=
1 J/kg
93
how determine damage related to ionizing radiation
Gy(RBE) = Sievert
94
RBE
relative biological effectiveness
95
Sievert
SI unit for effective dose
96
as energy is transformed into matter, what is formed?
unstable things, e= mc^2
97
fusion of hydrogen nuclei to form helium
1/1 p + 1/0 n --> 2/1 d
2 2/1 d---> 4/2 alpha
1/1 p + 1/1 p --> 2/1 d + 0/1 B
98
posititrons and electrons (blank) to release huge amounts of energy
annihilate each other
99
overall equation of positrons and electrons annihilation
4 1/1 p --> 4/2 He + 2 0/1 B
100
4 protons lose mass for form
alpha particle
101
mass of stable nucleus (blank) than free nucleons
less
102
BE
delta m c^2
103
radioactive ones on belt of stability
radionuclides
104
above belt of stability
neutron rich, beta decay
105
below belt of stability
neutron poor, positron emission
106
beta decay
gain proton
| 14/6 C --> 14/7 N + 0/-1 B
107
positron emission
10/6 C --> 10/5B +0/1 B
| lose proton
108
electron capture
11/6 C + 0/-1 B --> 11/5 B
lose proton
written opposite positron
109
alpha decay
234/92 U --> 4/2 alpha + 230/90 Th
| subtract 4 and 2
110
after 83 protons, all species are
radioactive
111
nuclei with (blank) tend to be more stable
even # protons and neutrons
112
nuclear fission involves
decomposition of U nucleus
113
produce > 1 neutron, process is
self-sustaining
114
radioactivity measured as
decay event/time
115
radioactivity is a
first order process
116
radioactivity rate =
decay events atom/sec times number of atoms
117
good for dating rocks
235 U and 207 Pb
118
biological effects of radiation
- forms of radiation can break chemical bonds
- produce radicals, free electrons, cations
- "ionizing radiation"
- cause cancer, birth defects, death
119
absorbed dose measures
ionizing radiation/mass
120
SI unit--->
G ray = 1 J/kg
121
Gy RBE=
Sievert
122
what occurs since alpha particles have a large mass?
blocked with paper
123
one way to have exposure to alpha particles is
radon gas
