I'm breaking a list questions into separated entries as bobbie7-ga
suggested (Thank you bobbie7-ga). Please provide the answer to the
following problems:

1) Suppose we let the exothermic reaction,

	2SO2(g) + O2(g) <--> 2SO3(g)

come to equilibrium. Then we decrease the temperature of the reaction
mixture, while holding the volume constant.

What will be the effect on the net amount of SO3(g) present ?



1. no change

2. a decrease

3. an increase

4. question cannot be answered without Kc or Kp values

5. question cannot be answered without delta H value


2) Consider the aqueous reaction

		A <--> B + C

	Adding a liter of water to the reaction flask will

1. not affect the number of moles of C

2. None is correct	

3. increase the number of moles of C

4. decrease the number of moles of C

5. have an effect depending on the value of Kc the number of moles of
C

Hello

1) In an exothermic reaction, the reaction gives off heat - therefore,
by removing heat from the system, the reaction will proceed more
towards reactants - a simple way to think of this is that putting in
more starting material leads to more products; putting in more
products, inhibits the production of products (shifts the reaction
towards the reactants).  Heat, here, is a product - thus less heat,
more products.

answer - 3

2) In this question, the equilibrium constant is given by:

    [C][D]
k = -------
     [A]

if we assume a concentration of 1 to start, then:

     1 * 1
k = --------  =  1  
        1

if we dilute the sample (assume that 1L dilutes the reaction by half),
the concentrations will half (or decrease even without our assumption
of half) and x will be used as the common factor for the amount of
change seen.

     (0.5 + x)(0.5 +x)
k = -------------------          solving for x gives 0.11
      (0.5 - x)

therefore, the concentration of C at equilibrium will be 0.61, up from
the 0.5 at the time of dilution, thus, diluting the reaction will
increase the concentration of the reactants, and the total number of
moles of each compound.  Note, this only works because the number of
moles of reactant is lower than the number of moles of product which
favors this direction of the reaction.

answer - 3


synarchy

references:  
description for problem 1:
http://www.psigate.ac.uk/newsite/reference/plambeck/chem1/p01101a.htm


a nice example for question 2:
http://www.madsci.org/posts/archives/apr2001/986332923.Ch.r.html

---

Request for Answer Clarification by jwheel-ga on 15 Oct 2003 19:14 PDT

Thank you, very much appreciated.

Would you like for me to close the question and rate it, or may I post
a few more questions (and pay you extra in form of an additional tip)
? You seem to answer very well and provide an explanation for your
answers. Thank you nevertheless if you reject this offer.

---

Clarification of Answer by synarchy-ga on 15 Oct 2003 19:46 PDT

I would be happy to answer more questions.

---

Request for Answer Clarification by jwheel-ga on 15 Oct 2003 20:00 PDT

Hello synarchy,

I have posted the additional problems in another 'Simple Chemistry
Problems' set,   if you have time and are willing to do the additional
work, please check them out. Thank you for your help, its very
inspiring to see such bright people.

---

Clarification of Answer by synarchy-ga on 15 Oct 2003 20:20 PDT

Thank you for the tip!!

Thank you very much, you are very helpful.