The boiling point of benzene is 353 . 23 K . When 1 . 80 g of non-volatile solute was dissolved in 90 g of benzene, the boiling point of is raised to 354 . 11 K . Calculate the molar mass of the solute. ( K b for benzene is 2 . 53 K Kg mol - 1 )

Given, The boiling point of pure benzene = 353 . 23 K The boiling point of the solution = 354 . 11 K The weight of the benzene W A = 90 g The weight of the solute W B = 1 . 80 g Molal boiling point elevation constant K b = 2 . 53 K Kg mol - 1 So, the elevation in boiling point ∆ T b = 354 . 11 - 353 . 23 = 0 . 88 K If the molar mass of the solute is M B , then ⇒ M B = K b × W B × 1000 ∆ T b × W A ⇒ M B = 2 . 53 × 1 . 80 × 1000 0 . 88 × 90 = 57 . 5 g mol - 1 The molar mass of the solute is 57 . 5 g mol - 1 .

E M B I B E

All In One ISC Chemistry Class 12>Chapter 2 - Solutions>Chapter Practice>Q 26

EASY

12th ICSE

IMPORTANT

Earn 100

Distinguish between the terms molality and molarity. Under what conditions are the molarity and the molality of a solution nearly the same?

Important Questions on Solutions

EASY

12th ICSE

IMPORTANT

All In One ISC Chemistry Class 12>Chapter 2 - Solutions>Chapter Practice>Q 27

How many grams of the concentrated nitric acid solution should be used to prepare

250 mL

of

2.0 M {HNO}_{3}

? (The concentrated acid is

70 % {HNO}_{3}

)

MEDIUM

12th ICSE

IMPORTANT

All In One ISC Chemistry Class 12>Chapter 2 - Solutions>Chapter Practice>Q 28

The

K_{H}

value for

{Ar}_{(g)}, {CO}_{2 (g)}, {HCHO}_{(g)}

and

{CH}_{4 (g)}

are

40.39, 1.67, 1.83 \times 10^{- 5}

and

0.413

respectively. Arrange these gases in the order of their increasing solubility and giving suitable reason.

EASY

12th ICSE

IMPORTANT

All In One ISC Chemistry Class 12>Chapter 2 - Solutions>Chapter Practice>Q 29

Why the solubility of the Glauber's salt

({Na}_{2} {SO}_{4} . 10 H_{2} O)

first increases upto

32.4 ° C

and then decreases?

EASY

12th ICSE

IMPORTANT

All In One ISC Chemistry Class 12>Chapter 2 - Solutions>Chapter Practice>Q 30

Consider the solute-solvent interaction and arrange the following compounds in the order of increasing solubility in ethanol with suitable explanations.