Download Worksheet for 4-29 - Iowa State University

Leaders: Shealyn
Course: Chem 178
Supplemental Instruction
Iowa State University
Instructors: Burnett/ Vela
Date: 4-29-14
1. Battery: self-contained ________ device containing one or more ______ cells. For
_______ cells placed in _____ (as shown) the voltage or potential is _______.
2. In the lead-acid battery used in
automobiles, shown in the figure,
each voltaic cell is 2 volts. To
achieve 12 volts, _____ cells are
placed in _____.
3. In the U.S. corrosion costs the economy roughly one-half to one trillion dollars annually,
_____% of the GDP.
4. Most metal cations have ______
(negative/positive) standard reduction
potentials, consequently they have a tendency
to become ________ (reduced/oxidized).
Which means that metals tend to spontaneously
_______(reduce/oxidize) in air.
5. Some metals form a(n) _____ layer barrier that
prevents further
_________(reduction/oxidation).
6. Cathodic protection: add a ____ (more/less) reactive metal such as ___ or ___ that
preferentially oxidizes and forces the iron to be the ______ (anode/cathode) and therefore
remains in its reduced form. Such metals must have a more _______ (positive/negative)
Eored potential.
7. The primary difference between a battery and a fuel cell is that a battery is
______________ and a fuel cell requires continuous ________(addition/removal)of
________(reactant/product) and _______(addition/removal) of
_______(reactant/product).
8. Fuel cells: electrochemical devices that use ______ to produce electrical _____.
9. We have pointed out that combustion reactions are ______ reactions. Therefore the fuels
used in combustion can be used to power fuel cells. Fuel cells can be very efficient in
converting chemical ________(potential/electrical) energy into
1060 Hixson-Lied Student Success Center  515-294-6624  [email protected]  http://www.si.iastate.edu
_______(potential/electrical) work relative to energy of combustion being converted into
work.
10. For nuclear processes, there is one criteria for spontaneity: if the reaction produces _____
(ΔE < 0), then the process is spontaneous (ΔSuniverse ___ (</>/=) 0).
11. nuclear processes are accompanied by ______ (small/large/average) amounts of energy.
12. Fission: a(n) _____(stable/unstable) nucleus _________ (decaying/combining) to form 2
or more more-stable nuclei
Fusion: 2 relatively ________(stable/unstable) nuclei combining to form a single more
______(stable/unstable) nucleus
Transmutation: the _________(decaying/combining) of one nucleus/isotope into a
different nucleus/isotope.
13. Define nucleon:
14. For light elements (up to atomic number ___), stable nuclei have ____ (1:1. 1:2, 2:1)
neutron to proton ratios. As the number of protons increases, stable isotopes have
_________(decreasing/increasing) neutron to proton ratios.
15. We also saw that nuclei with more than ___ protons are ________(stable/unstable).
16. Decay mechanisms for unstable nuclei:
a. _____ emission (reduces mass & charge of nuclei)
b. _____ emission (increases charge of nuclei, mass unchanged)
c. ______ ______ (decreases charge of nuclei, mass unchanged)
d. _____ emission (reduces charge of nuclei, mass unchanged)
17. Nuclei with ____ (even/odd) numbers of nucleons
are more stable.
18. Nuclei that are unstable are generally unstable for several possible reasons:
a. proton:neutron ratio too large or too many ______ (protons/neutrons)for
number of _______ (protons/neutrons)
b. proton:neutron ratio too small or too many _______ (protons/neutrons) for
number of _______ (protons/neutrons)
c. nuclei too large (>___ protons)
d. ____(even/odd) number of nucleons, protons, or neutrons
e. unfilled shell structure for nucleons
19. Gamma particles are ____less and ______less. They are a form of electromagnetic
radiation. Gamma particles are also called _______ (positrons/photons) and are emitted
in all nuclear reactions.
20. Complete and balance the following nuclear equations, identify the type of radioactive
decay, and deduce the source of nuclear instability of parent nuclei.
a.
239
94 Pu
40
4

 2  + ____
40
K 
 20 Ca + ____
b. 19
0
40
e  18 Ar
c. ____ + 1 
d.
14
6C

 ____ +
0
1 e