25. ms1=200g NaCl
C1=40℅
ms2=300g KCl
C2=20℅
mH2O=500g
C1=md1/ms1*100=> md1=C1*ms1/100=80g NaCl
C2=md2/ms2*100=>md2=60g KCl
mdf = md1+md2=60+80=140g
msf = ms1+ms2+mH2O=200+300+500=1000g
Cf=mdf/msf*100=140/1000*100=14℅
26. md=8 g zahăr
mH2O=72 g
ms = md+mH2O = 8+72=80g sol
C1=md/ms*100=8/80*100=10℅ [A]
msf = 80+8 = 88g sol
mdf = 8+8=16 g zahăr
C=mdf/msf*100=16/88*100=18,18℅ [B]
a) Soluția [B] se concentrează
b) [A] = 10℅ , [B] = 18,18℅
27. ms=50g
C=10℅
C=md/ms*100=>md=C*ms/100=10*50/100=5 g
ms=md+mH2O=>mH2O=ms-md=50-5=45g
mH2O/4=45/4=11,25g
msf = 5+11,25=16,25g sol
mdf = 5 g
Cf=mdf/msf*100=5/16,25*100=30,769℅
28. ms=250g sol
C=5℅
Cf=25℅
C=md/ms*100=>md=C*ms/100=5*250/100=12,5g
ms=md+mH2O=>mH2O=ms-md=250-12,5=237,5g
Cf*mH2Of=md(100-Cf) => mH2Of=md(100-Cf)/Cf = 12,5(100-25)/25 = 37,5g
mH2O evaporată = 237,5-37,5=200g
29. C=5℅
ms=150g sol
C=md/ms*100=>md=7,5g
msf = 150-25=125g sol
Cf=mdf/msf*100=7,5/125*100=6℅
30. ms=200g sol
C=20℅
+md2=10g
C1=md1/ms1*100=>md1=40g
mdf = md1+md2=40+10=50g
msf = ms1+md2=200+10=210g
Cf=mdf/msf*100=50/210*100=23,8℅