Question

Calculati concentratia masica a unei solutii care se obstinè prin dizolvarea a 4 mol de acid clorhidric īn 73 mol de apa!

Answer 1

c% = md x 100 / ms

n = nr moli = masa subst. / M moleculara subst.

M molec. apa = 18 g/mol, M molec acid clorhidric = 36,5 g/mol

=> m apa = 73 x 18 = 1314 g apa

=> m acid = 4 x 36,5 = 146 g

=> ms = md + m.apa = m.acid + m.apa = 146 + 1314 = 1460 g sol acid clorhidric

=> c% = 146 x 100 / 1460 = 10%

Answer 2

concentratia = c

c = md .100 : ms

md= masa subst. care se dizolva

MHCl=1+ 35,5=36,5---->1mol=36,5 g

MH2O=2 +16=18------>1mol=18 g

n=m: M

m=n.M=4.36,5=146 g HCl--------> acesta este md pentru solutie

md=146g HCl

ms= md +mapa

mapa ------> m=n.M=73.18=1314 g H2O

ms=146+ 1314=1460 g sol.

c=146.100: 1460=10 la suta