Question

Se amesteca doua solutii de alcool de concentratie 20%, respectiv, 40% , in raport masic 1:2 , obtinandu-se 900 g solutie. Calculeaza concentratia procentuala a solutiei rezultate.
REPEDE!

Answer 1

c1=md1/ms1*100
=>md1=ms1*20/100=0,2ms1
c2=md2/ms2*100
=>md2=ms2*40/100=0,4ms2
ms1+ms2=900
ms1/ms2 = 1/2 => ms2 = 2ms1
c% final = md final/ ms final * 100
md final = md1+md2 = 0,2ms1+0,8ms1=ms1
ms final = ms1+ms2=ms1+2ms1=3ms1
c% = ms1/3ms1*100 = 33,333%

Answer 2

x1 + x2 = 900 ==>x1+2x1=900==>3x1=900==>x1=300g solutie

x1/x2=1/2==>x2=2x1=2*300=600g solutie

Cp1=md1/ms1*100==>md1=Cp1*ms1/100=20*300/100=60g

Cp2=md2/ms2*100==>md2=Cp2*ms2/100=40*600/100=240g

mdf=60+240=300g

msf=900g

Cpf=mdf/msf*100=300/900*100=33.33%