Question

Se amesteca 500 g solutie NaOH 10% ( densitate = 1, 115 g/ ml) cu 300 ml soluție NaOH 16% ( densitate = 1, 181 g/ml) si cu 200g de apă. Calculați C% si Cm a soluției finale.

Answer 1

ms1 = 500g
C1 = 10%
ro1 = 1,115g/mL
Vs2 = 300mL
C2 = 16%
ro2 = 1,181g/mL
mH2O = 200g

C1 = md1/ms1×100 => md1 = C1×ms1/100 = 10×500/100 = 50g NaOH

ro2 = ms2/Vs2 => ms2 = ro2×Vs2 = 1,181×300 = 354,3g sol. NaOH

C2 = md2/ms2×100 => md2 = C2×ms2/100 = 16×354,3/100 = 56,688g NaOH

mdf = md1+md2 = 50+56,688 = 106,688g NaOH

msf = ms1+ms2+mH2O = 500+354,3+200 = 1054,3g

Cf = mdf/msf×100 = 106,88/1054,3×100 = Calculeaza !!!

ro1 = ms1/Vs1 => Vs1 = ms1/ro1 = 500/1,115 = 448,43 mL
VH2O = 200mL

Vsf = Vs1+Vs2 + VH2O = 448,43+300+200 = 948,43mL = 0,94843 L sol. NaOH

Cmf = mdf/M×Vsf = 106,688/(40×0,94843) = Calculeaza !!!