The coolant in automobiles is often a 50/50 % by volume mixture of ethylene glyc

Question

The coolant in automobiles is often a 50/50 % by volume mixture of ethylene glycol, HOCH2CH2OH, and water. At 20 degree C, the density of ethylene glycol is 1.1088 g/mL and the density of water is 0.9982 g/mL. Assuming that the volumes are additive, what is the expected freezing point of a 50/50(v/v)% ethylene glycol/water solution? Kf= 1.86 degree C/m for water. When 0.500 g of vitamin K is dissolved in 10.0 g of camphor (Kf = 40.0 degree C/m), the freezing point of the solution is 4.43 degree C lower than that of pure camphor. Assuming vitamin K is a nonelectrolyte in camphor, calculate its molar mass. Naproxen is a commercially important anti-inflammatory agent that can be isolated from the thyroid gland. A solution of 1.138 g of naproxen in 25.00 g benzene has an osmotic pressure of 4.00 atm at 20 degree C. The density of benzene is 0.8787 g/mL at this temperature. Calculate the molar mass of naproxen, assuming it remains intact upon dissolution and the density of the solution equals the density of pure benzene. 58) A 3.17 m solution of CaCl2 in water has a density of 1.24 g/mL. What is the molarity?

Explanation / Answer

a)let the volume of the solution be 100ml

so the volume of glycol=50=volume of water

so the number fo moles of glycol=50*1.1088/62

=0.894

number of moles og water=50*0.998/18

=2.77

so glycol is dissolved in water.

so the molality=0.894*1000/49.92

=17.9

so the expected freezing point=-1.86*17.9

=-33.31C

b)let the molar mass be x.so molality=0.5*1000/(x*10)

=50/x

so 4.43=40*50/x

or x=452.467 g/mol

5a) volume of benzene=25*0.8787

=21.9675 ml

so the concentration=1.138*1000/(m*21.9675)

so 4=1.138*1000/(m*21.9675) *1/12 *293

or m=230

b)convert it into litre and find the mass of water used to get the result

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