Chemistry 203
Exam 3
Study Sheet
The following topics are considered ‘fair game’ for the exam on Nov. 30th.
Thermodynamics (Chapter 19)
 Gibbs Free Energy (calculation and interpretation of)
 Free Energy over a temperature range
 Free Energy and the equilibrium constant (K)
 Free Energy and the reaction quotient (Q)
Electrochemistry (Chapter 20)
 Identifying species that are being oxidized, reduced, and are oxidation or
reduction agents.
 Balancing redox reactions in acidic and basic media.
 Voltaic cells – determination of cathodes, anodes, flow of electrons, and flow of
ions.
 Calculation of Ecell under standard conditions.
 Calculation of Ecell under non-standard conditions.
 Reduction half-potentials and their meanings.
 Free Energy, Equilibrium constants and emf.
 Use of the Nernst equation.
 Corrosion
Nuclear Chemistry (Chapter 21)
 Types of radioactive decay / balancing reactions.
 Patterns of nuclear stability
 Kinetics of radioactive decay
 Energy changes in nuclear changes
 Fission and fusion reactions
Chemistry of Materials (End of Chapter 12)
 Semiconductors
 Nanomaterials
Sample questions:
The following are sample exam questions.
1. Balance the following redox reactions in base:
a. B2Cl4 + OH-  BO2- + Cl- + H2O(l) + H2(g)
b. F5SeOF + OH-  SeO42- + F- + H2O(l) + O2(g)
c. XeF6 + OH-  XeO64- + F- + H2O + Xe(g) + O2(g)
2. Determine the equilibrium constant and G at 25C for the following reactions.
a. Ag+(aq) + Fe2+(aq)  Fe3+(aq) + Ag(s)
b. MnO2(s) + 4H+(aq) + 2Cl-(aq)  Mn2+(aq) + 2H2O(l) + Cl2(g)
3. Technicium-99 has a 210,000 year half life. When bombarded with neutrons, it
forms Techinicium-100 and then has a half life of 16 seconds and decays into
Ruthenium-100. Write the nuclear reactions for these processes. If one was to
start with 454g (1lb) of Technicium-99 which gets completely converted to
Technicium-100, how much 100Tc would be left over after 5 minutes?
4. Describe how semiconductors are used to make solar cells (light harvesters) and
light emitting diodes (LEDS). How are their designs and functions different?
5. An equilibrium mixture at 727C contains 0.276 moles of H2, 0.276 moles of
CO2, 0.224 moles of CO, and 0.224 moles of H2O.
CO2(g) + H2(g)  CO(g) + H2O(g)
a. What is the value of G at 727C?
b. In what direction will a net chemical change occur is the concentrations were
changed to 0.0500 moles of CO2, 0.0700 moles of H2O, 0.0400 moles of CO, and
0.0850 moles of H2O?
c. Will there be a change in G when this occurs? If so, what is its magnitude and
sign?