The exam will be held Friday April 27, in SL 140, from 11:00 until 11:50 am. Bring a calculator. The exam will contain a mixture of multiple-choice and “show your work” problems. Partial credit for the latter will be given ONLY if you show your work. Some of the problems are designed to test your ability to solve chemical problems (such as those in E&G, and in the online homework). Other questions will be designed to test your understanding of the chemical concepts discussed in lecture. I will supply potentially useful information that may include (but is not limited to): equations (e.g., PV = nRT), constants (e.g., gas constant etc.), necessary values of DH, and a “bare bones” periodic table.
The exam will emphasize the material covered in chapters 5 and 6. Below is a list of the concepts/skills that I expect you to study for the exam. This list is not guaranteed to be complete. It is a very good idea to review homework problems and the following topics in preparation for the exam.
General:
You should be able to:
1) set up and use stoichiometric relationships:
balancing equations
calculating formula weights/molar masses
convert masses of reactants and products to moles (and vice versa)
identify the limiting reagent in a reaction
use concentration information (molarity etc.)
2) perform unit conversions (e.g., atm to mm Hg or Pa; g/cm3 to kg/m3;
etc.)
3) recall that bond formation
releases energy and bond cleavage absorbs energy
Your answers must ALWAYS have the
appropriate units and, where requested, the correct number of significant
digits
Concepts to study:
The Ideal Gas Law: PV = nRT
What happens to P as V decreases at T = constant; what happens to V if P & T = constant and n increases? etc.
Know how to calculate moles of gas given P, V, T
Calculation of density of gas given specific conditions of P, T, etc.
What assumptions are used in the Ideal Gas Law and what are the limits of applicability?
How do real gases differ from ideal gases? (i.e., interactions between particles and volume of particles)
Kinetic Theory of Gases
How is kinetic energy of particles related to Temperature?
Graham’s Law of Effusion
Identify an unknown gas by comparison of effusion rate to the effusion rate of a known gas
Know relationship between mole fraction and partial pressures
Review Lab #2 (Identification of Unknown Metal) and understand calculations required to ID the metal from your data
Kinetic energy
Calculation of kinetic energy (from: ½ mv2)
Internal energy of a system
What are: “system”, “surroundings”, “universe” in terms of thermochemistry
Internal energy related to motions of particles (atoms/molecules) of the system
State functions
Use of real or imagined pathways to calculate DH (includes Hess’s Law concepts)
Using the information in thermochemical equations
What is sign of q or DH for exothermic reaction?
What is sign of q or DH for endothermic reaction?
Setting up appropriate conversion factors (e.g., mol/kJ or kJ/mol) given a balanced thermochemical equation
Calculating heat of reaction from X grams of reactant, or grams X needed to produce Y kJ of heat
Heat capacity and specific heats
Definition of heat capacity (or specific heat)
Application to heat transfer reactions (e.g., calorimetry experiments) where -qrxn = qcal (or more generally: qabsorbed = -qreleased)
Hess’s Law
Using two or more thermochemical equations to derive a thermochemical equation for the reaction of interest
Proper manipulation of the signs and coefficients for the DH terms
Standard enthalpies of formation (DHºf)
Calculating DHºreaction from DHºf information (a table of relevant DHºf data will be provided)
Preparation Strategy:
- Review any sections of the online HW assignment #1 that gave you problems.
- Work as
many problems
as you can (this works best after you have read the textbook). If you are pressed for time in solving the suggested
homework problems in E & G, try the “Cumulative Skills” problems at the end
of the chapter first. If you can solve
these you are probably in good shape to move on to the next chapter. If these problems give you some difficulty,
try some of the earlier problems, or review the material in the reading, or seek assistance from me. Here are specific suggestions for review
problems in your text:
Chapter
Chapter 6: 1, 2, 5, 6, 11, 13, 31, 39, 51, 55, 57, 61,
67, 71, 73, 79, 81, 89-103odd, 109, 115, 119-125odd.
- Here is a link to some practice multiple
choice questions similar to those that might appear on the exam