Ocean water typically contains approximately 3.5 g of mostly NaCl per 100.0 mL o
ID: 1050177 • Letter: O
Question
Ocean water typically contains approximately 3.5 g of mostly NaCl per 100.0 mL of solution and has an approximate density of 1.03 g/ml. Note: the molar masses of water and sodium chloride are 18.0 g and 58.5 g. the density of pure water is 1.00 g/ml; the universal gas constant R is 0.0821 L-atm/mol-K. Calculate the vapor pressure of this solution if the vapor pressure of pure water at 25degreeC is 0 0313 atm. Calculate the osmotic pressure of this solution. The van't Hoff factor is approximately 1.95.Explanation / Answer
d)
Po = 0.0313
mass of NaCl= 3.5 g
density = 1.03 g/mL
mass of solution= 1.03 g/mL * 100 mL = 103 g
mass of water = 103 g – 3.5 g = 99.5 g
moles of NaCl = 3.5/58.5 = 0.06 mol
moles of H2O = 99.5/18 = 5.53 mol
mole fraction of H2O = 5.53 / (5.53 + 0.06) = 0.989
p = pO*x
p = 0.0313 * 0.989 = 0.03096 atm
e)
C = number of moles of NaCl / volume
= 0.06 / 0.1 L
= 0.006 M
P = i*C*R*T
= 1.95*0.006*0.0821*298
=0.286 atm
Answer: 0.286 atm
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