Question

cata soda caustica se foloseste intr-o reactie chimica daca concentratia solutiei scade la jumatate? S-au folosit initial 75g solutie de concentratie 20%

Answer 1

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