A 5 % solution (by mass) of cane sugar in water has freezing point of 271 K . Calculate the freezing point of 5 % glucose in water if freezing point of pure water is 273 . 15 K .

Sugar cane contains sucrose thus molar mass of sugar = 342 g mol - 1 The 5 % of sugarcane solution means 5 g of sucrose in 100 g of solution. Weight of solvent can be calculated as follows: ∴ w 1 = 100 - 5 = 95 g Molality of sugar solution = w 2 / M 2 w 1 / 1000 = 5 × 1000 342 × 95 = 0 . 1538 m ∆ T f for sugar solution = 273 . 15 - 271 = 2 . 15 K ∆ T f = K f × m K f = 2 . 15 0 . 1538 = 13 . 9791 Km - 1 Molar mass of glucose is 180 g / mol The 5 % of glucose solution means 5 g of glucose in 100 g of solution. Weight of solvent can be calculated as follows. ∴ w 1 = 100 - 5 = 95 g molality = w 2 / M 2 w 1 / 1000 = 5 180 × 1000 95 = 0 . 2924 m ∆ T f = K f × m = 2 . 15 0 . 1538 × 0 . 2924 = 4 . 09 K Freezing point of glucose = 273 . 15 - 4 . 09 = 269 . 06 K

An antifreeze solution is prepared from 222 . 6 g of ethylene glycol C 2 H 6 O 2 and 200 g of water. Calculate the molality of the solution. If the density of the solution is 1 . 072 g mL - 1 , then what shall be the molarity of the solution?

Mass of solute(Ethylene glycol) = 222 . 6 g The molar mass of solute (Ethylene glycol) C 2 H 4 OH 2 = 12 × 2 + 4 + 2 16 + 1 = 62 g mol - 1 Number of moles of solute= Mass of solute Molar mass = 222 . 6 62 = 3 . 59 Mass of solvent= 200 g Molality = Moles of solute Mass of solvent in grams × 1000 = 3 . 59 200 × 1000 = 17 . 95 mol kg - 1 Total mass of the solution = 422 . 6 g Volume of the solution= Mass of the solution density of the solution = 422 . 6 1 . 072 = 394 . 21 ml Molarity= Number of moles of solute Volume of solution × 1000 = 3 . 59 394 . 2 × 1000 = 9 . 1 mol . L - 1

E M B I B E

Chemistry Crash Course (Based on Revised Syllabus-2023)>Chapter 1 - Solutions>Sample Paper>Q 53

MEDIUM

12th CBSE

IMPORTANT

Earn 100

What is the effect of temperature on the solubility of glucose in water?

Important Questions on Solutions

MEDIUM

12th CBSE

IMPORTANT

Chemistry Crash Course (Based on Revised Syllabus-2023)>Chapter 1 - Solutions>Sample Paper>Q 54

Ibrahim collected a

10 mL

each of fresh water and ocean water. He observed that one sample labelled

" P "

froze at

0 ° C

while the other "

Q

" at

- 1.3 ° C

. Ibrahim forgot which of the two,

" P "

or

" Q "

was ocean water. Help him identify which container contains ocean water, giving rationalisation for your answer.

MEDIUM

12th CBSE

IMPORTANT

Chemistry Crash Course (Based on Revised Syllabus-2023)>Chapter 1 - Solutions>Sample Paper>Q 55

Calculate Van't Hoff factor for an aqueous solution of

K_{3} [Fe (CN)_{6}]

if the degree of dissociation

(α)

is

0.852 .

What will be boiling point of this solution if its concentration is

1

molal?

(K_{b} = 0.52 K

kg / mol)

MEDIUM

12th CBSE

IMPORTANT

Chemistry Crash Course (Based on Revised Syllabus-2023)>Chapter 1 - Solutions>Sample Paper>Q 56

What type of deviation from Raoult's Law is expected when phenol and aniline are mixed with each other? What change in the net volume of the mixture is expected? Graphically represent the deviation.

MEDIUM

12th CBSE

IMPORTANT

Chemistry Crash Course (Based on Revised Syllabus-2023)>Chapter 1 - Solutions>Sample Paper>Q 57

The vapour pressure of pure water at a certain temperature is