c= mdx100/ ms, ms= md+m,apa
Presupun ca la reactie nu participa apa, deci m,apa nu se modifica .
Claculez masa de soda din solutia initiala:
20/100= md/ 75----> md= 15g soda
Dupa reactie, dispar x grame soda : md'= 15- x si ms'= 75- x
c'= 10%---.> 10/100= (15-x)/ (75-x)
10(75-x)=100(15-x)----> calc x, g soda consumata in reactie