The reaction
SO2 + 1/2O2 -->SO3
has kp equal to 6.55 at 627C. what is the value of kc at this temperature?
how do you set this up?
The formula is on page 1, about 1/3 the way down the page.
To find the value of Kc at a given temperature, you need to use the relationship between Kp and Kc. Kp is the equilibrium constant expressed in terms of partial pressures, while Kc is the equilibrium constant expressed in terms of molar concentrations.
The balanced chemical equation for the reaction given is:
SO2 + 1/2O2 --> SO3
To set up the expression for Kc, you need to write the equation using concentrations instead of partial pressures. Start by converting the partial pressures of the gases to molar concentrations:
P(SO2) = [SO2]
P(O2) = [O2]
P(SO3) = [SO3]
Next, replace the partial pressures in the expression for Kp with their respective molar concentrations:
Kp = (P(SO3))/((P(SO2))(P(O2)))
Kc = ([SO3])/(([SO2])([O2]))
Now, you need to determine the relationship between Kp and Kc at the given temperature. According to the ideal gas law, the ratio of partial pressure to concentration is equal to the quotient of the molar amount and volume:
(P/V) = (n/V) = [C]
Since the volume is constant, the concentrations can be related to partial pressures:
[P] = [C]
Therefore, at constant temperature and volume, the ratio of Kp to Kc for any reaction is equal to the total pressure at equilibrium:
Kp = Kc(RT)^(Δn)
Where R is the ideal gas constant, T is the temperature, and Δn represents the change in the number of moles of gaseous products minus the change in the number of moles of gaseous reactants.
In the given reaction, there is no change in the number of moles (Δn = 0), so the relationship between Kp and Kc is simplified to:
Kp = Kc
Therefore, the value of Kc at 627°C would also be 6.55.