Question

39.8g of a mixture of potassium chloride KCl and potassium trioxochlorate(V), KClO3 were heated to a constant mass. If the residue weighed 28.9g, what was the percentage mass of the potassium chloride in the mixture

Answer 1

KClO₃ + 2KCl → 3KClO

$KClO_3$  - x gram

2 moles of Potassium trioxochlorate produces 2 moles of Potassium chloride

$\frac{x}{122.5}$ Moles will produce same amount of KCl

$\\$$\frac{x}{122.5}\ mole \ KCl=\frac{x}{122.5}\times 74.5\ g\ KCl$

write an equation

$39.8-x+\frac{74.5x}{122.5}=28.9$

x=27.82g

m(KCl)=39.8-27.82=11.98g

$the percentage mass=\frac{11.98}{39.8}\times100=30.10$ %