Question

4.Din 150 grame solutie de concentratie 15% sau evaporat 25 grame apa .
Determina concentratia solutiei obtinute . 

Answer 1

100 g solutie.................15 g .............85 g apa
150 grsolutie..................x g substanta.............yg apa

x=15x150/100=22.5 g substanta

y=127.5 g apa 
daca se evapora 25 g apa raman 127.5-25=102.5 g apa

102.5+22.5 g subst=125 g solutie ramasa dupa evaporare

125 g solutie................22.5 g subst
100g solutie.................z g subst

z=2250/125=18   

deci conc solutiei obtinute e 18%