Q76E - Chemistry (OpenStax)

Question

The phosphorus pentoxide used to produce phosphoric acid for cola soft drinks is prepared by burning phosphorus in oxygen.

 

(a) What is the limiting reactant when 0.200 mol of P₄ and 0.200 mol of O₂ react according to

                        P₄ + 5O₂ ⟶ P₄O₁₀

(b) Calculate the percent yield if 10.0 g of P₄O₁₀ is isolated from the reaction.

Step-by-Step Solution

Answer

a) Limiting reactant is O₂ 

 

b)  Percent yield will be 88 % of P₄O₁₀ 

Determine limiting reactant

P₄        +      5O₂ ⟶ P₄ O₁₀

0.200         0.200

mol             mol

 

1 Mol of P₄ gives 1moles of O2.   Therefore, 

 

(0.200 mol P₄ x 5 mol of O₂)/ 1 mol P4 

 = 1 mol of O₂

 

Here, I have 0.200 mol of O₂ but I need 1 mol of O₂. Means 0.200 will get used up in the reaction. That’s why O₂ is the limiting reactant. 

 

Determine percentage yield

% yield =   actual yield x 100

               theoretical yield

 

Actual yield = 10 g ------given

Molar mass of P₄O₁₀   =  283.88

 

Theoretical yield =   0.200 mol O₂ x   1 mol P₄O₁₀    x             283.88g P₄O₁₀

                                                                  5 mol O₂                        1 mol P₄O₁₀

 

                            = 11.355 g P₄O₁₀

 

 

% yield =   actual yield x 100

               theoretical yield

             \(\begin{aligned}{\underline{\phantom{xx}}} &= \frac{{10.0}}{{11.355}} \times 100\\ &= 88\% \,\,{P_4}{O_{10}}\end{aligned}\)