Chemistry Class 11 NCERT Solutions: Chapter 1 Some Basic Concepts of Chemistry Part 2

Download PDF of This Page (Size: 642K)

Q: 3 Determine the empirical formula of an oxide of iron which has 69.9% iron and 30.1% Dioxygen by mass.

Answer:

% of iron by mass = 69.9 % [Given]

% of oxygen by mass = 30.1 % [Given]

Relative moles of iron in iron oxide:

Relative moles of oxygen in iron oxide:

Simplest molar ratio of iron to oxygen:

Q: 4 calculate the amount of carbon dioxide that could be produced when

(i) 1 mole of carbon is burnt in air.

(ii) 1 mole of carbon is burnt in 16 g of Dioxygen.

(iii) 2 moles of carbon are burnt in 16 g of Dioxygen

Answer:

The balanced reaction of combustion of carbon can be written as:

(i) As per the balanced equation, 1 mole of carbon burns in 1 mole of Dioxygen (air) to produce 1 mole of carbon dioxide.

(ii) According to the question, only 16 g of Dioxygen is available. Hence, it will react with mole of carbon to give 22 g of carbon dioxide. Hence, it is a limiting reactant.

(iii) According to the question, only 16 g of Dioxygen is available. It is a limiting reactant. Thus, 16 g of Dioxygen can combine with only 0.5 mole of carbon to give 22 g of carbon dioxide.

Q: 5. Calculate the mass of sodium acetate required to make 500 mL of 0.375 molar aqueous solutions. Molar mass of sodium acetate is

Answer:

0.375 M aqueous solution of sodium acetate

mL of solution containing 0.375 moles of sodium acetate

∴Number of moles of sodium acetate in 500 mL

mole

Molar mass of sodium acetate

Q: 6 Calculate the concentration of nitric acid in moles per litre in a sample which has a density, and the mass per cent of nitric acid in it being

Answer:

Mass percent of nitric acid in the sample

Thus, 100 of nitric acid contains of nitric acid by mass.

Molar mass of nitric acid

∴ Number of moles in

Volume of of nitric acid solution

Concentration of nitric acid

∴ Concentration of nitric acid