Colligative properties : Consider these two solutions: Solution A is prepared by
ID: 104252 • Letter: C
Question
Colligative properties :
Consider these two solutions: Solution A is prepared by dissolving 5.00 g of MgCl, in enough water to make 0.250 L of solution, and Solution B is prepared by dissolving 5.00 g of KCl in enough water to make 0.250 L of solution. Which direction will solvent initially flow if these two solutions are separated by a semipermeable membrane? 12. Assuming that the volumes of the solutions described in question #12 are additive and ignoring any effects that gravity may have on the osmotic pressure of the solutions, what will be the final volume of solution A when the net solvent flow through the semipermeable membrane stops? 13. a+ 2 eyExplanation / Answer
12)
step 1: find osmotic pressure of MgCl2
Molar mass of MgCl2 = 1*MM(Mg) + 2*MM(Cl)
= 1*24.31 + 2*35.45
= 95.21 g/mol
mass of MgCl2 = 5.00 g
we have below equation to be used:
number of mol of MgCl2,
n = mass of MgCl2/molar mass of MgCl2
=(5.0 g)/(95.21 g/mol)
= 5.252*10^-2 mol
volume , V = 0.250 L
we have below equation to be used:
Molarity,
M = number of mol / volume in L
= 5.252*10^-2/0.25
= 0.2101 M
T = 298 K
we have below equation to be used:
P = i*C*R*T
P = 3.0* 0.2101*0.0821*298.0
P =15.4 atm
step 2: find osmotic pressure of KCl
Molar mass of KCl = 1*MM(K) + 1*MM(Cl)
= 1*39.1 + 1*35.45
= 74.55 g/mol
mass of KCl = 5.00 g
we have below equation to be used:
number of mol of KCl,
n = mass of KCl/molar mass of KCl
=(5.0 g)/(74.55 g/mol)
= 6.707*10^-2 mol
volume , V = 0.250 L
we have below equation to be used:
Molarity,
M = number of mol / volume in L
= 6.707*10^-2/0.25
= 0.2683 M
T = 298 K
we have below equation to be used:
P = i*C*R*T
P = 2.0*0.26827632461435275*0.0821*298.0
P =13.1 atm
Since osmotic pressure is more for MgCl2, solvent will flow to the side of MgCl2
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