Chemistry Class 11 NCERT Solutions: Chapter 1 Some Basic Concepts of Chemistry Part 3

Q: 7. How Much copper can be obtained from 100 g of copper sulphate Equation ?

This structure is 1 mole of copper sulphate CuSO4

Structure of Copper Sulphate CuSO4

This structure is 1 mole of copper sulphate CuSO4

Answer: Equation contains 1 mole of copper.

Molar mass of Equation

Equation

Equation

Equation contains Equation of copper.

Equation

∴Amount of copper that can be obtained from Equation

Equation

Q: 8 Determine the molecular formula of an oxide of iron in which the mass per cent of iron and oxygen are 69.9 and 30.1 respectively. Given that the molar mass of the oxide is Equation

This structure is number of moles of iron present in oxide

Structure of Molecular Iron to Oxygen Oxide

This structure is number of moles of iron present in oxide

Answer: Mass percent of iron Equation

Mass percent of oxygen Equation

Number of moles of iron present in the oxide Equation

Equation

Number of moles of oxygen present in the oxide Equation

Equation

Ratio of iron to oxygen in the oxide,

Equation

Equation

Equation

Equation

∴ The empirical formula of the oxide is Equation

Empirical formula of oxide Fe2O3

Structure of Molar Mass Oxide

Empirical formula of oxide Fe2O3

Empirical formula mass of Equation

Molar mass of Equation

Equation

Equation

Equation

Molecular formula of a compound is obtained by multiplying the empirical formula with n. Thus, the empirical formula of the given oxide is Equation

Hence, the molecular formula of the oxide is Equation

Q: 9 Calculate the atomic mass (average) of chlorine using the following data:

Abundance and molar mass of Cl isotopes
Abundance and molar masses of Cl isotopes

% Natural Abundance

Molar Mass

Equation

Equation

Equation

Equation

24.23

36.9659

This structure is example of Average atomic mass

Structure of Average Atomic Mass

This structure is example of Average atomic mass

Answer: The average atomic mass of chlorine Equation

Equation

Equation

Equation

∴ The average atomic mass of chlorine Equation

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