Kp=1.78 at 250 degrees for the decomposition reaction, PCl5(g)->PCl3(g)+Cl2(g. Calculate the percentage of reactant that remains if 10.0 moles of starting material are placed in a closed vessel at this temperature and 2.00 atm pressure. Also, determine the value of Kc for this reaction at 250 degrees.
Set up an ICE chart and substitute into the Kp expression, then solve for x. For converting Kp to Kc, look in your text or notes for the formula to do that.
To calculate the percentage of reactant that remains, we first need to calculate the equilibrium constant (Kc) using the given equilibrium constant at a different temperature (Kp=1.78 at 250 degrees).
The general equation to convert between Kp and Kc is:
Kp = Kc(RT)^(Δn)
Where:
- R is the ideal gas constant (0.0821 L·atm/(mol·K))
- T is the temperature in Kelvin (250 degrees = 523 K)
- Δn is the change in the number of moles of gaseous products minus the number of moles of gaseous reactants.
Looking at the reaction, we can see that Δn = (1 + 1) - 1 = 1 (since 1 mol of PCl5 decomposes to produce 1 mol of PCl3 and 1 mol of Cl2).
Let's calculate Kc using the given Kp value:
Kc = Kp / (RT)^(Δn)
Substituting the values:
Kc = 1.78 / (0.0821 * 523)^(1)
Kc = 1.78 / 42.9663
Kc ≈ 0.0414
Now, to determine the percentage of reactant that remains, we can use the equation for the reaction quotient (Qc):
Qc = [PCl3] * [Cl2] / [PCl5]
At equilibrium, Qc = Kc. We can set up the following expression:
Kc = [PCl3] * [Cl2] / [PCl5]
We can rearrange the equation to solve for the concentration of PCl5:
[PCl5] = [PCl3] * [Cl2] / Kc
Since we started with 10.0 moles of PCl5, we can calculate the equilibrium concentration using the equation:
[PCl5]equilibrium = (10.0 - [PCl5]remaining)
Now, substituting the values, we have:
(10.0 - [PCl5]remaining) = ([PCl3]equilibrium) * ([Cl2]equilibrium) / Kc
We need additional information to determine the exact concentrations of the products and reactants at equilibrium, such as initial amounts or equilibrium concentrations. Without this information, we cannot provide a specific answer.
You would need to provide the initial amounts or information about the equilibrium concentrations of the products and reactants in order to proceed with the calculation and determine the percentage of reactant remaining.