Question

1.Peste 300g solutie acid colhidric de adauga 200g apa ,iar concentratia devine 20%.Ce concentratie a avut solutia initiala
2.Intr-un vas se toarna 500ml solutie de soda caustica20%si ρ(ro)=1,22 g/cm³apoi se adauga 200g soda caustica de concentratie 12%.Ce concentratie procentuala are solutia finala.
3.Cate grame de apa sunt necesare pentru a dilua 800ml solutie de acid clorhidric 20% ( ρ=1,1 g/cm³) pana la o concentratie de 10%.
Puteti sa scrieti si cu prescurtari ,dau puncte

Answer 1

1. Cf=mdf/msf*100=>mdf=20*500/100=100g

Ci=mdi/msi*100=100/300*100=33,33℅

2. ro1=ms1/Vs1=>ms1=ro1*Vs1=1,22*500=610g sol NaOH

C1=md1/ms1*100=>md1=C1*ms1/100=20*610/100=122g NaOH

C2=md2/ms2*100=>md2=C2*ms2/100=12*200/100=24g NaOH

mdf = md1+md2=122+24=146g

msf = ms1+ms2=610+200=810g

Cf=mdf/msf*100=146/810*100=Calculează!

3. ro=ms/Vs=>ms=1,1*800=880g sol HCl

C=md/ms*100=>md=C*ms/100=20*880/100=176g HCl

ms=md+mH2O=>mH2O=ms-md=880-176=704g

C*mH2O=md(100-C) => mH2O=md(100-C)/C = 176(100-10)/10= 1584g

mH2O necesară = 1584-704=880g