ms1=50g +mH2O c(final)=5%
c1=40% ----------------------------->
c=md x 100 / ms
c1 = md1 x 100 / ms1
md1= c1 x ms1/ 100
md1= 40 x 50 / 100
md1 = 20 g NaOH pur
md(final)=md1
ms(final)=ms1+mh2o
ms(final)=ms1+a
c(final) = md(final) × 100 / ms1+a ==> C(final)x(ms1+a)=100md(final)
C(final) ×ms1+c(final) × a=100mdf
a= 100mdf-cf × ms1
a= 100x20-5×50
a=2000-250
a=1750 g h2o adaugat