006 10.0 points
Given the following equilibrium data at 973 K
MgCl2(s) +12O2(g) ⇀↽MgO(s) + Cl2(g) Kp = 2.95 atm
MgCl2(s) + H2O(g) ⇀↽MgO(s) + 2HCl(g) Kp = 8.40 atm
Calculate the equilibrium constant Kp at 973 K for 2Cl2(g) + 2H2O(g) ⇀↽O2(g) + 4HCl(g) .
1. 24.8
2. 8.11
3. 5.50
4. 11.4
5. 2.85
-->Id guess that you would to a hess law kind of thing to the Kp's, but i really dont understand it.
Consider the following decomposition reaction at 700 K.
2CaSO4(s) --> 2CaO(s) + 2 SO2(g) + O2(g)
If Kp = 0.032 at this temperature, what
will be the equilibrium overall pressure starting
from pure CaSO4(s)?
1. 0.20 bar
2. 0.011 bar
3. 0.60 bar
4. 0.40 bar
5. 0.22 bar
-->I dont understand how theres a starting pressure from a solid. How do you relate Kp to pressure without any starting pressures?
You are right to treat the first problem like Hess's law. Remember that when we combine reactions by adding them, the K's multiply and when you reverse a reaction, the K is inverted. So you will probably need to reverse one, add them together and possibly multiply them by a coefficient ( K ^ power).
ReplyDeleteRemember that solids are not in the equilibrium constant expression. So the solids are all left out and the initial value of SO2 and O2 are both 0. The values then will be 2x and x respectively at equilibrium. Remember the question asks about total pressure. Solve for x, plug into 2x and x, and then sum them.
I get them now, thanks
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