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CHEMISTRY LEVEL 3


1. GAS LAWS
2. THE MOLE: Formulae and Chemical Equations
3. ORGANIC CHEMISTRY 1
4. NITROGEN AND ITS COMPOUNDS
5. SULPHUR AND ITS COMPOUNDS
6. CHLORINE AND ITS COMPOUNDS
7. A guide to chemical tests based on this module
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THE MOLE: Formulae and Chemical Equations: Molar solutions



2.0 THE MOLE: Empirical and Molecular formula


2.6 Molar solutions

In Section 2.5, we expressed concentration in g/dm3. But it can also be expressed in moles per litre (mol/dm3). A solution that contains 1 mole of a substance in 1 litre is a molar solution (1M). One that contains 2 moles per litre is two-molar (2M) and so on. M stands for mol/dm3.


Questions 2.6

  1. Determine the concentration in mol/dm3 of a solution containing (a) 5.85 g of sodium chloride in 1 dm3 (b) 5.85 g of the salt in 250 ml (c) 2.925 g of the salt in 500 ml (Na = 23; Cl = 35.5).
  2. Determine the concentration in mol/dm3 of a solution containing (a) 40 g of sodium hydroxide in 500 ml (b) 5 g in 250 ml (H = 1; O = 16; Na = 23)
  3. Determine the concentration in mol/dm3 of a solution containing 98 g of sulphuric acid in 1 dm3 (b) 49 g of sulphuric (VI) acid in 250ml (H = 1; O = 16; S = 32).
  4. The concentration of a certain dilute hydrochloric acid solution is 2M. What is the mass of hydrochloric acid in a 25 ml sample of the solution? (H = 1; Cl = 35.5.)

Answers to Questions 2.6