Question

M-ра=300гW(Hcl)=20%m(NAOH)-?

Answer 1

Дано
m(ppa HCL)=300 g
W(HCL)=20%
-----------------------
m(NaOH)-?
m(HCL)=300*20%/100%=60 g
  60       X
HCL+NaOH-->NaCL+H2O    M(HCL)=36.5 g/mol , M(NaOH)=40 g/mol
 36.5    40
X=60*40 / 36.5=65.75 g
ответ 65.75 г 

Answer 2

M вещ.=300г. *0,2=60г
m(Naoh)=300-60=240г