Answer to Question #95744 in Physical Chemistry for George

Question #95744
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
1
Expert's answer
2019-10-02T08:03:49-0400

Let the mass of KClO3KClO_3 be x gram

Reaction of decomposition is given by:

2KClO32KCl+3O22KClO_3\to 2KCl+ 3O_2

2 moles of Potassium trioxochlorate produces 2 moles of Potassium chloride

So,

x122.5\frac{x}{122.5} Moles will produce same amount of KCl

\\x122.5 mole KCl=x122.5×74.5 g 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 g28.9\ g

So,

39.8x +74.5x122.5=28.939.8-x\ +\frac{74.5x}{122.5}=28.9

0.391836x=10.9x=27.8177 g0.391836x=10.9\\x=27.8177\ g

Initial masso f Potassium chloride = 38.9x=11.0823 g KCl38.9-x=11.0823 \ g\ KCl

Percentage composition of KCl = 11.082339.8×100=27.844%\frac{11.0823}{39.8}\times100=27.844\%


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