2.5 moles of Cl2 reacts with a large excess of P4. The actual yield of PCl5 is 0.50 moles. What is the percent yield?

P4(s) + 10 Cl2 (g)-> 4 PCl5 (g)

10Cl2 + P4 ==> 4PCl5

Convert 2.5 mol Cl2 to mols PCl5 using the coefficients in the balanced equation. That is the theoretical yield of the reaction.
Then % yield = [theoretical yield/actual yield]*100.
The actual yield is given in the problem as 0.5 mol.

To find the percent yield, we need to compare the actual yield to the theoretical yield. The theoretical yield is the maximum amount of product that can be obtained from a given amount of reactant.

First, we need to determine the stoichiometry of the reaction. From the balanced equation, we can see that 1 mole of P4 reacts with 10 moles of Cl2 to produce 4 moles of PCl5.

Given that we have 2.5 moles of Cl2, we can calculate the theoretical yield of PCl5 using the stoichiometry:

2.5 moles Cl2 x (4 moles PCl5 / 10 moles Cl2) = 1 mole PCl5

So, the theoretical yield of PCl5 is 1 mole.

Now, we can calculate the percent yield using the formula:

Percent Yield = (Actual Yield / Theoretical Yield) x 100

Plugging in the values, we have:

Percent Yield = (0.50 moles / 1 mole) x 100 = 50%

Therefore, the percent yield of PCl5 is 50%.