Quiz 2 material (14.4-14.7, ch 15)

[Robert Zellmer]

Quiz 2 will cover the following:

Chapter 14 (14.4-14.7), Chapter 15 (15.1-15.7)

There is some overlap with quiz 1 for chapter 14 (as in knowing
what a rate law is - Section 14.3).

*Section 14.3: *

Technically this section was on the first quiz and while you might
not be directly quizzed on this stuff you still need to know these things.

Know how to obtain a rate from data and how to use rate data to determine
the rate law using the method of initial rates.  This is shown in the book
in sample ex 14.6 (and the practice exercise) and my notes.  You really need
to learn how to do this using the second example I used in lecture (the long
one).  If you don't you will have problems with some of the end-of-chapter
exercises (especially the last one for section 14.3).

Remember, rate laws can depend on concentration of reactants, products and
catalysts.  The orders of substances in the rate law can be whole numbers,
simple fractions, negative (usually seen for products and inhibitors).  To
get the overall order you simply add the orders for everything in the rate
law.  Also, remember in general you can't write the rate law from the 
balanced
chemical equation.  It must be determined experimentally. The ONLY time you
can write a rate law from a balanced eqn is if you know the reaction is an
elementary reaction (a single-step mechanism) and you don't know this by
simply looking at the reaction.

*Section 14.4:*

Know what an integrated rate equation is for zero-order, 1st-order and
2nd-order reactions and be able to use them.  Know what the half-life is
for zero-order, 1st-order and 2nd-order reactions.  This is in section 14.4.
The equations for zero-order are in the notes. There are a couple of
questions in the chapter 14 "handouts" about zero and 2nd order reactions
on my class web page (see "Notes" link).  Be able to do the special problem
passed out in class and sent via e-mail.

*Section 14.5: *

Understand the relationship between temp., activation energy (Ea) and rate
constant (Arrhenius eqn.) and the rate of the reaction. Understand how all
this relates to collision theory and transition state theory.

*Section 14.6: *

Understand mechanisms and how to obtain a rate law from a mechanism,
rate laws for elementary reactions, recognize intermediates,
and what molecularity means.

Remember, steps in a mechanism are always written as elementary processes,
which means the rate law for a step can be written from the balanced eqn
for that step.  This is the ONLY time you can write the rate law from a
balanced eqn.

*Section 14.7: *

Know what catalysts are and the four common characteristics of catalysts,
homogeneous and heterogeneous catalysis, how catalysts work and be able
to recognize a substance as a catalyst or intermediate in a mechanism. Know
how a catalyst affects rate and how this can be seen using the Arrhenius 
eqn.

You can find the handouts mentioned above at

*Chapter 14 - Chemical Kinetics - Handouts* 
<http://www.chemistry.ohio-state.edu/%7Erzellmer/chem1220/notes/ch14houts.pdf>


*Homework coverage (you should be able to all problems in the given 
ranges):*

For those of you using the 14th edition the quiz covers sections 14.1-14.4
You should be able to do homework problems 14.1-14.8, 14.17-14.50,
14.89-14.103, 14.117

For those of you using the 13th edition the quiz covers sections 14.1-14.4
You should be able to do homework problems 14.1-14.8, 14.17-14.50,
14.89-14.103, 14.117

For those of you using the 12th edition the quiz covers sections 14.1-14.4
You should be able to do homework problems 14.1-14.8, 14.17-14.52,
14.97-14.109, 14.119

For those of you using the 11th edition the quiz covers sections 14.1-14.4
You should be able to do homework problems 14.1-14.6, 14.13-14.46,
14.83-14.93, 14.104

*For the on-line homework:*

Do ch 14 (14.4-14.7) homework review.  Remember there are the DSM questions
and review problems for Ch 14 (plus a tutorial which isn't for credit).

Don't forget the extra homework problems "handout".  They can also be found
on my web page at the Notes link (see above) or Homework link where you will
also find the solutions,

*CH 14 - Kinetics, Extra Problems and Solutions* 
<http://www.chemistry.ohio-state.edu/%7Erzellmer/chem1220/homewk/ch14hmwk_add.pdf>

*You will get the integrated rate equations and half-life eqns. on the 
quiz.**
**They will not be in any particular order nor will the half-life eqns**
**necessarily be in the same order as the integrated rate equations.*


*Sections 15.1-15.5: *

You need to understand how to set up an expression for the equilibrium
constant, K and how to use it.  Understand how to set up K for heterogeneous
equilibria (when you have pure solids and liquids involved in the 
equilibrium).
What substances appear in the equilibrium constant expression? Gases and 
solutes
in solution but not pure solids or liquids.  How do you know if 
something is a
pure solid or liquid?  If there's and (s) or (l) for the state symbol in the
balanced equation.

What does the magnitude of K tell you?  Does the reaction go to completion
and by how much (mostly products or "essentially only" products)? Does the
reaction "not occur to any great extent" and how little reaction occurs
(mostly reactants or "essentially only" reactants)?  Are there appreciable
amounts of reactants and products at equilibrium?

Remember K depends on the form of the balanced equation and you can
relate the K for one form of the balanced equation to another.   When you
multiply and eqn by some factor the K for the new reaction equals the old
K RAISED to that factor (you do NOT multiply the K by that factor).
(e.g. K_rev = 1/K_for or K_for^-1which makes sense since to get the reverse
rxn you are essentially multiplying the forward rxn by -1).
Know the relationship between equilibrium constants when you add several
balanced equations to get a new balanced equation (the K's of the eqns
being added are multiplied together to get the K for the resulting new rxn).

Know how to use an equilibrium (ICE) table and use it to determine K from
equilibrium concentrations.

Know how to relate Kp and Kc.

*Section 15.6: Applications of Equilibrium Constants*

Understand the reaction quotient, Q, and how you use it with K to predict
whether the reaction is at equilibrium or not and if not which direction
does it proceed to reach equilibrium.

Know how to use an ICE table to calculate equilibrium conc. starting with
initial conc. and the equilibrium constant, K.

On the quiz, if you need to use an ICE table, you MUST SHOW the WORK
and the ICE table.  When making any assumptions you should show that your
assumptions are okay (less than 5% error).  If the percent error is greater
than 5%, you need to solve the problem in a more exacting way (solve a
quadratic, method of successive approximations, etc.). You must show this
work.  If you don't, you will not get full credit.

*Section 15.7: Le Chatelier's Principle*

Understand how changing conc. shifts a reaction
(AWAY from ADDED, TOWARD REMOVED).  Remember adding or
removing (small amounts, but not all) of a pure solid or pure liquid will
not shift a reaction.  Removing all of a pure solid or pure liquid will 
shift the
reaction (toward the removed substance - you have to have some of the
solid or liquid to be at equilibrium when they are present in the rxn).
Adding or removing a pure liquid which is also the solvent will cause a
shift due to an indirect effect (e.g. adding solvent decreases the conc.
of the solutes causing the reaction to shift toward more moles in solution,
similar to what happens for gases when the pressure decreases due to a
volume inc.).  I discussed this in relation to exp 19 in class.
Conc. changes do NOT affect the numerical value of K.

Know how changing pressure (due to volume changes) effects a reaction.
Increasing pressure (by reducing the volume) shifts the reaction toward
fewer moles of gas.  Decreasing pressure (by inc. the volume) shifts
the reaction toward more moles of gas.  Changing volume for a gas is
essentially changing the concentration of the gases. Decreasing volume
increases the conc. of the gases and shifts the reaction to the side
with fewer moles in solution (remember, a gas mixture is a solution).
Pressure changes do NOT affect the numerical value of K.

Remember, adding an inert (non-reacting) gas to a reaction involving
gases will increase the total pressure but will NOT cause a shift in
the reaction because the partial pressures of the gases involved in
the reaction do not change.

Something similar also occurs in reactions taking place in a liquid solution
environment. When the volume of solution changes the reaction will shift
if there is a change in moles of dissolved solutes.  If the volume is
increased by adding solvent the reaction will shift toward more moles
of solutes.  This is like decreasing pressure by inc. volume for gases,
the reaction shifts toward more moles of gas.

Also, know how changing temperature shifts a reaction AND changes the 
numerical
value of the equilibrium constant, K (changing conc. and pressures do 
not affect
the numerical value of K).  How does the change in the forward and 
reverse rate
constants (rates) cause the shift in the equilibrium and affect K for both
exothermic and endothermic reactions for elementary reactions?  Remember,
temperature changes have a bigger affect on reactions with bigger Ea.

*Homework coverage (you should be able to all problems in the given 
ranges):**
*
For those of you using the 11th - 14th editions the quiz covers ch 15.
You should be able to do all homework problems in ch 15.

*For the on-line homework:*

Do ch 15 (15.1-15.7) homework review.  Remember there are the DSM questions
and review problems for Ch 15 (plus a tutorial which isn't for credit).


Don't forget the extra homework problems.  They can be found on the web at
the Homework link on the class web page (CH 15 - Extra ICE Table 
Problems and
Solutions),

*CH 15 - Extra ICE Table Problems and Solutions* 
<http://www.chemistry.ohio-state.edu/%7Erzellmer/chem1220/homewk/ch15_extra_problems.pdf>


Dr. Zellmer
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