Chemistry: Chapter 9 - Chemical Calculations

9.1 Calculations from Chemical Reactions
A balanced chemical equation shows the important facts about a reaction:

• The reactants
• The products
• The ration of the amounts (in moles) of the reactants and the products
• The state of the reactants and products indicated.

The relationship between the amounts of reactants and products involved in a chemical equation is know as the stoichiometry of the reaction.

9.2 The Volumes of Reacting Gases
Volume of a gas is proportional to the number of moles of the gas, and vice versa.

9.3 Limiting Reactants
The reactant that is completely used up in a reaction is known as the limiting reactant.
The reactants that are not used up are called the excess reactants.

9.4 The Concentration of a Solution
The concentration of a solution is given by the amount of a solute dissolved in a unit volume of a solution.
Concentration (g/dm³) = Mass of Solute in Grams / Volume of Solution in dm³

Molar Concentration
Concentration (mol/dm³) = number of moles of solute / volume of solution in dm³

Concentration (mol/dm³) = concentration (g/dm³) / Molecular mass of solute

9.5 Volumetric Analysis
Volumetric analysis is a technique used to determine the volumes of solutions that react together. In volumetric analysis, titration is performed to get the results.