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

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Q: 1 Calculate the molecular mass of the following:

Example of molecular mass for carbon dioxide

Structure of Molecular Mass

Example of molecular mass for carbon dioxide

(i) Equation

Molecular Atomic mass of 2 hydrogen + 1 oxygen

Structure of Molecular Mass of H2O

Molecular Atomic mass of 2 hydrogen + 1 oxygen

(ii) Equation

Molecular Atomic mass of 1 carbon +2 oxygen

Structure of Molecular Mass of CO2

Molecular Atomic mass of 1 carbon +2 oxygen

(iii) Equation

Molecular Atomic mass of 1 carbon + 4 hydrogen

Structure of Molecular Mass CH4

Molecular Atomic mass of 1 carbon + 4 hydrogen

Answer:

(i) Equation

The molecular mass of water, Equation Equation

Equation

Equation

Equation

Equation

(ii) Equation

The molecular mass of carbon dioxide, Equation

Equation

Equation

Equation

Equation

(iii) Equation

The molecular mass of methane, Equation

= Equation

Equation

Equation

Equation

Q: 2 calculate the mass percent of different elements present in sodium sulphate Equation

Na2SO4 is a typical ionic sulfate, containing Na+ ions and SO42- ions

Structure of Sodium Sulphate Na2SO4

Na2SO4 is a typical ionic sulfate, containing Na+ ions and SO42- ions

This Structure is sodium hydroxide & copper sulfate & Solid copper hydroxide in colouriess sodium sulfate solution.

Structure of Sodium Sulphate

This Structure is sodium hydroxide & copper sulfate & Solid copper hydroxide in colouriess sodium sulfate solution.

Answer:

The molecular formula of sodium sulphate is Equation

Molar mass of Equation

Equation

Mass percent of an element Equation

∴ Mass percent of sodium:

Equation

Equation

Equation

Mass percent of sulphur:

Equation

Equation

Equation

Mass percent of oxygen:

Equation

Equation

Equation

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