0.100 mol of SO2 and 0.100 mol of O2 are introduced in a flask of 1.52 L. When in equilibrium, 203 is found to be 0.0916 mol. Determine kp.
2S03(g) <-> 2SO(g) + O2(g)
In order to solve this question 1st I made an ICE table and I got the values
2SO3 <-> 2SO + 02
I .100 .100
C .1- 0.0916 .1-.0458
E 0.0916 .0084 .0542
.0916/1.52 .0084/1.52 .0542/1.52
=.060M =.0055M =.0357M
Then I substitued each value into the kp expression and solved for the Kp. Is this correct?
The boards don't recognize any space AFTER the first one but you can still space if you use periods; for example, as in
..........2SO3 ==> 2SO2 + O2.
initial....0.........0.1....0.1
change....+2x........-2x...-x
equil.....+2x........0.1-2x.0.1-x
The equilibrium values look ok to me for SO3 and O2. For SO2, I think you have thrown away the last number which I wouldn't do. 0.1-0.0916 = 0.00840. (OK, so it's a zero but you shouldn't throw it away.)
To that point you are ok. What you have calculated, and called Kp, actually is Kc. moles/L = M and you substituted into the Kc expression and solved for Kc.
What you need to do next is to add all of the moles to find total moles, then find the mole fraction of each gas.
XSO3 = moles SO3/total moles = ??
XSO2 = moles SO2/total moles = ??
XO2 = moles O2/total moles = ??
Next you want the partial pressure of each. That is
PSO3 = XSO3*Ptotal
PSO2 = XSO2*Ptotal
PO2 = XO2*Ptotal.
Do you have a value for Ptotal in the problem, an equilibrium pressure given, or a temperature given in the problem/
Sorry my ICE table came out wrong.
It is actually suppose to be
2SO3 <-> 2SO + 02
I 0 .100 .100
C 0 .1- 0.0916 .1-.0458
E 0.0916 .0084 .0542
No I wasn't, but can I just use the pressure formula of P() = nRT/V and then just add all of them together?
Okay I think I figured out how to do it all. Thanks for explaining.
You don't have a T; what will you substitute for T in P = nRT/V. If you have a total P you can calculate partial pressures of each then solve for Kp.
Yes, your approach is correct. To determine the value of Kp, you need to calculate the equilibrium concentrations of each species and then substitute those values into the expression for Kp.
In this case, you correctly set up an ICE table:
2SO3 <-> 2SO + O2
I 0.100 0.100
C 0.1 - 0.0916 0.1 - 0.0458
E 0.0916 0.0084 0.0542
Then, you divided each concentration by the volume of the flask to calculate the molarities:
SO3: 0.0916 mol / 1.52 L = 0.060 M
SO: 0.0084 mol / 1.52 L = 0.0055 M
O2: 0.0542 mol / 1.52 L = 0.0357 M
Next, you substitute these equilibrium concentrations into the expression for Kp:
Kp = ( [SO]^2 * [O2] ) / [SO3]^2
Kp = (0.0055^2 * 0.0357) / (0.060^2)
Calculating this expression will give you the value of Kp for the system at equilibrium.