Question

Calculeaza masa carbonatuluide sodiu si volumul apei necesare pentru pregatirea a 200g de solutie cu partea de masa de Na2CO3 egala cu :a )3%,b)5%
Ajuta-ma va rooog !

Answer 1

a. R/e:
ω(Na2Co3)=$\frac{m(Na2Co3)}{m(sol)}$
m(Na2Co3)=ω(Na2Co3)* m(sol)
ω=ω%/100%= 3%/100%=0,03
m(Na2Co30)=0,03*200g=6g
m(H2O)= m(sol)-m(sub)=200g-6g=194g

Answer 2

Cp=md/ms*100

a) 3=md/200*100==>md=3*200/100=6g

ms=md+mH2O==>mH2O=ms-md=200-6=194g

b) 5=md/200*100==>md=5*200/100=10g

ms=md+mH2O==>mH2O=ms-md=200-10=190g