12.3g of P4 reacts with cl2 to produce 50.0g of PCl3. what is the percent yield?

Answer 1

Correct answer: 91.68%

Step 1: Write the balanced equation for P₄ + Cl₂ --> PCl₃

*Given that only the amount of one reactant is given, it assumed that P₄ is the limiting reactant, which dictates how much product can be made.

Balanced reaction is : P₄ + 6Cl₂ --> 4PCl₃

Step 2: Convert mass of P₄ to grams (divide given mass in grams by molar mass of P₄)

12.3g P₄ x (1 mole P₄÷ 123.88g P₄) = .09928 mol P₄

Step 3: Multiply by the mole ratio between the limiting reactant (P₄) and the product (PCl₃)

.09928 mol P₄ x (4 mol PCl₃/ 1 mol P₄) = .3972 mol PCl₃ created

Step 4: Multiply the moles of product by the molar mass of the product (PCl₃) to determine the theoretical yield

.3972mol PCl₃ x (137.32g PCl₃/ 1mol PCl₃) = 54.54g PCl₃

To find the % yield

Divide the experimental yield (stated in the problem) by the theoretical yield (which was just previously determined).

50.0g PCl₃ / 54.54g PCl₃ = .9168 x 100% = 91.68%

Answer 2

To find % yield, we need to know the theoretical yield and the actual yield. We are given the actual yield as 50.0 g, so we now must find the theoretical yield:

(1) write the correctly balanced equation:

P₄ + 6Cl₂ ==> 4PCl₃ ... balanced equation

(2) convert 12.3 g P4 to moles and calculate theoretical yield of PCl3 in moles:

12.3 g P4 x 1 mol P4/123.9 g = 0.0993 moles P4

0.0993 moles P4 x 4 moles PCl3/mole P4 = 0.3972 moles PCl3 formed theoretically

(3) covert moles PCl3 to grams PCl3 theoretically formed:

0.3972 moles PCl3 x 137.3 g/mol = 54.5g PCl3 = theoretical yield

(4) calculate % yield as actual yield/theoretical yield (x100%):

50.0 g / 54.5 g (x100%) = 91.7% yield