Question

se amesteca 400g soda caustica cu concentratie 20% cu 600g soda caustica concentratie 30%.Ce concentratie procentuala are solutia finala

a)28%        b)26%      c)25%

Answer 1

ms1=400 g, c1=20% => md1=80 g
ms2=600 g, c2=30% => md2=180 g
cf=(mdf/msf)*100 => 
Cum mdf=md1+md2 => mdf=260 g
msf = ms1+ms2 => msf= 1000 h
cf= (260/1000)*100 = 26%.

Formula, ti-o reamintesc, pt conc procent este: Conc. procent= $\frac{ m_{d} }{ m_{s} } *100$.

Answer 2

Scrii formula generala c%=md/ms*100 si calculezi md pt fiecare solutie
md1=400*20/100=80 g
md2=600*30/100=180 g
md final = md1+md2=180+80=260 g
ms final = ms1+ms2=400+600=1000 g
c% finala=md final/ms final * 100 = 260/1000 * 100 = 26% deci raspunsul b