Răspunsuri

2014-04-22T16:05:25+03:00
Se da
c1=10%, ms1=300 g;
c2=20%;
Se cere
md2=?;

Formula: c=(md*100)/ms;

Aplicam:
  c1=(md1*100)/ms=>md1=(c1*ms)/100;
  md1=3000/100=30 g;

  c2=[(md1+x)*100]/(ms1+x) ; //x=cantitatea de substanta ce trebuie adaugata
  20=[(30+x)*100]/(300+x);                       
  20*(300+x)=(30+x)*100;  //am facut produsul mezilor=produsul extremilor
300+x=(30+x)*5;
300+x=150+5x;
150=4x;
x=150/4=75/2;
(md2=) x=32,5 g soda pura;
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