Răspuns:
%O= 100-31,83-28,98=39,19
transform raportul de mase in raport de moli
n,K:n,Cl:n,O= 31.83/39 : 28,98/35,5 : 39,19/16
=0,8161 : 0.8161 : 2,45 impart prin cel mai mic numar
= 1 : 1 :3
KClO3 p= 90%
p=m,px100/m,i-----> m,p= 136,1x90/100g= 122,5g KClO3 pur
2KClO3----> 2KCl + 3O2
2x122,5g........2x74,5g
122,5g..................x
x=74,5gKCl
xplicație: