Chapter 11, Problem 94A

Interpretation Introduction

Interpretation:

Percent yield of Zr to be determined

Concept introduction:

Zirconium is produced and purified by using Van Arkel process.

In first step impure Zr is heated with Iodine to form ZrI₄. In second step ZrI₄ decomposes to pure Zr.

Answer to Problem 94A

Theoretical yield of Zr is 6.85 g

Percent yield is 72.99%

Explanation of Solution

Step 1: write balance chemical equation

$\begin{array}{l}ZrI4(s)\to Zr(s)+2I2(g)\\ 45g5g\end{array}$

Step 2: convert mass of reactant to moles

$\begin{array}{c}MolarmassofZrI4=598.83g/mole\\ Moles=\frac{Mass}{Molarmass}\\ MolesofZrI4=\frac{45}{598.83}=0.075moles\end{array}$

Step 3: Convert moles of reactant to moles of product using mole ratio

1 mole of ZrI₄ produce = 1 moles of Zr

0.075 moles of ZrI₄ produce = 0.075 moles of Zr

Step 4: Convert moles of product to mass (theoretical yield)

$\begin{array}{c}Molar\text{}massofZr=91.22g/mole\\ Mass=Molarmass\times Moles\\ MassofZr(Theoreticalyield)=91.22\times 0.075=6.85g\end{array}$

Actual yield = 5 g (given)

$\begin{array}{c}PercentYield=\frac{Actualyield}{Theoreticalyield}\times 100\\ =\frac{5}{6.85}\times 100=72.99\%\end{array}$