M,KOH= 56g/mol
M,K2O= 94g/mol
1mol........1mol......2mol
K2O + H2O----> 2KOH
94g........18g.........2x56g
47g.......x= 9g.........y=56g
m,apa ramasa= 253-9=244g
c= mdx100/ms= mdx100/(md+m,apa)
c= 56x100 / (56+244)=...........................calculeaza !!!!!!