Question

In a lab, 33 g of potassium chloride is formed from 60.0 g of potassium chlorate decomposing. Calculate the theoretical yield and percent yield for this experiment.

Answer 1

Answer: The theoretical yield and percent yield for this experiment are 40 g and 82% respectively.

Explanation:

$2KClO_3\rightarrow 2KCl+3O_2$

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number $(6.023\times 10^{23})$ of particles.

To calculate the moles:

$\text{Moles of potassium chloride}=\frac{\text{Mass of potassium chloride}}{\text{Molar mass of potassium chloride}}=\frac{33g}{74.5g/mole}=0.44moles$

$\text{Moles of potassium chlorate}=\frac{\text{Mass of potassium chlorate}}{\text{Molar mass of potassium chlorate}}=\frac{66g}{122.5g/mole}=0.54moles$

According to stochiometry:

2 moles of $KClO_3$ produce = 2 moles of $KCl$

0.54 moles of $KClO_3$ should produce = $\frac{2}{2}\times 0.54=0.54moles$ of $KCl$

Thus theoretical yield is $moles\times {\text {Molar mass}}=0.54mol\times 74.5g/mol=40g$

But Experimental yield is 33 g.

${\text {percentage yield}}=\frac{\text {Experimental yield}}{\text {Theoretical yield}}\times 100\%$

${\text {percentage yield}}=\frac{33g}{40g}\times 100\%=82\%$

The theoretical yield and percent yield for this experiment are 40 g and 82% respectively.