Calculate the normal freezing point of a sample of sea water containing 3 8% NaCl and 0 12% MgCl2 by - Chemistry - Solutions

Question

Calculate the normal freezing point of a sample of sea water
containing 3 8% NaCl and 0 12% MgCl2 by mass (Cryoscopic Constant
for water = 1 86K/m)

Kumar Sarang · Accepted Answer

Let the mass of solution be 100 gMass of NaCl =3
8 gMass of MgCl2=0
12 gMass of water  =100-3 8-0 12=96
08 gNo
 of moles of NaCl =mass/molar mass =3
858 5=0 0649 molesNo
 of moles of MgCl2 =0 1295 2=0
0012 moles Total no
 of moles of solute  =0 0649 +0
0012 =0
0661 molesMolalit of solution = Moles of solute kg of solvent=0
06610 0960=0
6885 mΔTf =KbmwhereΔTf is depression in freezing pointΔTf = 1
86 × 0 6885 =1
2806 KThusNormal freezing point of sea water = 273-1
2806 =271 71 K

Calculate the normal freezing point of a sample of sea water containing 3.8% NaCl and 0.12% MgCl2 by mass.(Cryoscopic Constant for water = 1.86K/m)