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 Message 1 of 2 in Discussion 
From: MSN NicknameAlbert1145  (Original Message)Sent: 9/3/2008 9:48 AM
Q1) A salt M2X3 has a Ksp value of 8.44x10-15. What is the millimolar (mM) concentration of X2-in a saturated solution of this salt?
I got 0.0018

Q2) What is the percent of CsCl by mass in a 0.86 M CsCl solution that has a density of 1.091 g/mL?
I got 13.58

Q3) If the change in entropy of the surroundings for a process at 455 K and constant pressure is -345 J K-1, what is the quantity of heat absorbed by the system in kilojoules?
I have no idea how to do this one

Q4) How is the equilibruim position of this reaction affected by increasing the pressure?
C(s) + H2O(g) + heat <-> Co(g) + H2(g)

I'm thinking since solids don't participate in the reaction, the equation will increase in its reactant because less molecules in the system will reduce its pressure.

Q5) At a particular temperature, K=3.75 for the following:
So2(g) + No2(g) <-> SO3 + NO(g)
Would the equilibruim shift if the gases in the flask were compressed?

If what I'm thinking in question 4 is correct, then I suppose the equation will not shift in any direction.

Albert


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 Message 2 of 2 in Discussion 
From: MSN Nickname·Steve·Sent: 9/3/2008 8:55 PM
1.  Correct.

2.  You have 0.86 mol of CsCl per 1000 mL of solution.  The grams of CsCl is (0.86 mol)(168.358 g/mol)  =  144.788 g.  The grams of solution (1000 mL) is (1000 mL)(1.091 g/mL)  =  1091 g.  The percent by weight CsCl will be the grams of CsCl divided by the total mass of the solution, X 100.

3.  For this problem, just plug into the formula,  ΔSsurr  =  –ΔHsys / T.

4.  When the total pressure of all gaseous substances in the reaction is increased, done by compressing the reaction vessel volume, for example, then the reaction responds by going in the direction which "relieves" the pressure, which is toward the side that has the fewest gas molecules.  The number of gas molecules on each side of the reaction is given by the coefficients in front of the gaseous substances.  In this reaction, you have 1 mole of gaseous reactant (1 H2O) and two moles of gaseous products (1 CO and 1 H2).  Therefore, the reactant side has the fewest gaseous molecules.

5.  If there is the same number of gaseous substances on each side, then the reaction does not go in the forward or reverse direction when the total pressure is increased.
 
 
Steve