m=densitXvolum
m=50x1.22=61 g solutie
61 g solutie.................6.1 g hidroxid de sodiu
100g solutie......................x=10 g
conc procent. a primei solutii e 10%
100 g solutie.........................40 g NaOH
139 gsolutie..........................y g NaOH
y=55.6 gNaOH pur
55.6+6.1=61,7 gr NAOH
54.9 gr apa+83.4 g=138.3 gr apa
masa solutiei este 61.7+138.3 =200 g
200 g..........................61.7gr. NaOH
100g..............................z
z=6170/200= 30.85
deci conc. procent =30.85 %