Answer to Question #95744 in Physical Chemistry for George

Question

39.8g of a mixture of potassium chloride,kcl, and potassium trioxochlorate were heated to a constant mass. If the residue weighed 28.9g .what was the percentage mass of the potassium chliride in the mixture? (K39, CL=35.5,O=16) hint KCL is not decomposed on heating. Pls in need the answer

Answer 1

Let the mass of $KClO_3$ be x gram

Reaction of decomposition is given by:

$2KClO_3\to 2KCl+ 3O_2$

2 moles of Potassium trioxochlorate produces 2 moles of Potassium chloride

So,

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

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

Now final mass =initial mass of KCl +mass of KCl produced due to decomposition = $28.9\ g$

So,

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

$0.391836x=10.9\\x=27.8177\ g$

Initial masso f Potassium chloride = $38.9-x=11.0823 \ g\ KCl$

Percentage composition of KCl = $\frac{11.0823}{39.8}\times100=27.844\%$