61/,
Vs = 400 mL sau 400 cm3 sau 0,4 L
Cm = md/VsxM
M(etanol) = 46 g/mol
Cm = niu/Vs => niu = CmxVs = 0,4x8 = 3,2 moli etanol
Cm.final = niu/Vs.tot = 3,2/(0,4+1,2) = 2 M
Cm = roxc%x10/miu
=> c%.finala = Cmxmiu/rox10
= 2x46/0,8x10 = 11,5% => A.
63/.
se aplica regula dreptunghiului / amestecurilor
c1=60% ---------------------> 30-20= 10 parti sol 60%
l l
l c.final=30% l
l l
c2=20% --------------------> 60-30= 30 parti sol 20%
-----------------------------------------
total parti = 40 parti sol. finala 30%
=>
40 parti sol. finala .... 10 parti sol 60% ....... 30 parti sol 20%
a g sol 60% ...............300 g sol 20%
=> a = 100 g sol. 60% => B.
