Question

mixture of KCL and KCLO3 has a mass of 2.565 grams. the mixture is heated and the KCLO3. is decomposed. after cooling it mass is found to be 1.987g. A) calculate the mass of oxygen lost from the mixture?B) calculate the number moles of O2 lost from the mixture .C) calculate the number of moles of Kclo3in the orginal mixture. d) calculate the mass of KClO3 in the orginal mixture. E) calculate the percentage of KClO3 in the orginal mixture?

Answer 1

Let the mass of KClO3 be x g

then the mass of KCl is 2.565-x g

Molar mass of KClO3=122.5 g/mol

Molar mass of KCl=74.5 g/mol

Initial moles of KCl = (2.565-x)/74.5

Moles of KClO3=x/122.5

On heating KClO3

KClO3 -> KCl + 1.5 O2

initial x/122.5

final 0 x/122.5 (x/122.5)*1.5

After heating moles of KCl = x/122.5 + (2.565-x)/74.5

and we know that O2 has escaped and hence the mass left is of KCl only

then

Mass of Mix =(x/122.5 + (2.565-x)/74.5)*74.5 g=1.987 g

gives

x=1.475 g

Hence

Mass of KClO3=1.475 g

Mass of KCl=2.565-1.475=1.09 g

And Moles of KClO3=1.475/122.5=0.012

a) Mass of O2 lost =1.5*0.012*32=0.576g

b) Moles of O2 lost =1.5*0.12=0.018

c) Moles of KClO3=1.475/122.5=0.012

d) Mass of KClO3=1.475g

e) % of KClO3 =(1.475/2.565)*100=57.5 %

Please do give a thumbs up as it matters a lot and in case there are doubts leave a comment.