\"I cricket 10:41 AM 83% d. What is the freezing point of a saturated solution o

Question

"I cricket 10:41 AM 83% d. What is the freezing point of a saturated solution of 1-butanol in water K' for water 1860.7m 2. Calcium chloride absorbs water from the air to form calcium chloride dihydrate. Because it is highly hygroscopie, anhydrous cakium chloride is often used as a dessicant to absorb water from the air, How many grams of water can be absorbed by 250.g of anhydrous calcium chloride? 3. ucose solution is 52 38%. The density of solution The mass % of water in a saturated 123g/mL a. What are the mole fractions of water and glucose in this solution? b. What is the molarity of the solution? What is the molality of the solution? d. BONUS: Glucose is a non-lonizing, mnon-volatile solute. Whart is the vapor pressure o water above this solution?

Explanation / Answer

1.

a)1-butanol is a nonelectrolyte.

b)Given, 7.9g of 1-butanol in 100g water makes a satuated solution i,e 7.9% of solution of the 1-butanol makes a saturated solution.

here, we assume that the density of the solution is 1gm/ml

So,in 1000g or in 1kg of water 1-butanol should be added to make 7.9% solution is = (7.9*1000)/100 = 79g

Now, molar mass of 1-butanol= (12*4+10*1+1*16)g/mol= 74g/mole

so,79 g 1-butanol = 1.07 mol of 1-butanol

Now, molality means no of moles of solute dissolved in 1Kg of water.

so,clearly 7.9% of 1-butanol solution means 1.07 moles of 1-butanol is dissolved in 1 Kg water i,e its molality is 1.07 molal

c)Given,the density of the solution is = 0.9866g/ml

now,the mass of the 1 ml of the solution= 0.9866g

so,the mass of the 1000 ml of the solution = (0.9866*1000) = 986.6 g

At first of the question it is given it is 7.9% solution of 1-butanol.

now 100 gm of the solution contain = 7.9 g 1-butanol

so, 986.6 gm of the solution contains = (7.9* 986.6)/100 = 77.94 g of 1-butanol

so,in 1000 ml solution 77.94 g 1-butanol is dissolved.

now, molar mass of 1-butanol = 74g/mole

now,77.94 g 1butanol is = (77.94/74) = 1.05 moles of 1-butanol.

so,in 1000 ml solution 1.05 moles of 1-butanol is dissolved i.e molarity of the solution is 1.05 (M)

d)The solution is 1.07 molal.

now, the freezing point of pure water is 0C0

now the freezing point will be depressed for the solution

depression of the freezing point =- (kf * molality) (given kf of the solution is 1.860C/molal

= -(1.86 0C/molal* 1.07 molal) =- 1.9902 or -2.0 0C.

so,the freezing point of the solution is = (0-2.0)= -2.00C

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