Gay Lussac’s of combining volumes states that gases react in simple ratio with one another and to volumes of the products provided that temperature and pressure remain constant. In this article, you will understand how to apply this law in calculation by studying the following examples below: 1. 2H 2 + O 2 → H 2 O In the reaction above, what volume of hydrogen would be left over when 300cm 3 of oxygen and hydrogen are exploded in a sealed tube? 1cm 3 of oxygen = 2cm 3 of hydrogen 300cm 3 of oxygen = 2 x 300 = 600cm 3 Volume of left over = 1000 – 600 = 400cm 3 2. Calculate the volume of carbon (II) oxide required to react with 40cm 3 of oxygen. 2CO + O 2 → 2CO 2 1cm 3 of oxygen = 2cm 3 of CO 40cm 3 of oxygen = 2 x 40 = 80cm 3 3. Calculate the volume of residual gases that would be produced when 100cm 3 of sulphur (IV) oxide reacts with 20cm 3 of oxygen 2SO 2 + O 2 → 2SO 3 1cm 3 of O 2 = 2cm 3 20cm 3 of O 2 = 2 x 20 = 40cm 3
The collision theory shows that the rate of a chemical reaction depends on the frequency of the effective collisions between reactant particles. So any factor that can influence one or all following · The energy content of the particles · The frequency of the collision of the particles · The activation energy of the chemical reaction Can also affect the rate of chemical rate and such factors are · Nature of reactants · Concentration / pressure(for gas) of the reactants · Surface area of reactants · Temperature of reaction mixture · Presence of light · Presence of catalyst Nature of Reactants : The rate of reaction is affected by the chemical nature of the reactants because the energy content of different substances is not the same. For example, zinc reacts very fast with dilute hydrochloric acid to liberate hydrogen while gold does not show any sign of reaction. Concentration of