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
Quantitative analysis deals with the determination of the amount of each component in a sample of matter. It is divided into two which include: a. Gravimetric analysis b. Volumetric analysis Gravimetric analysis : is interested in the measurement of mass of the substances. Volumetric analysis : is interested in the measurement of the volume of solutions. Titration is the method used in volumetric analysis. This is done by careful addition of standard solution from a graduated container until the reaction is complete. A complete reaction is indicated by a colour change in the resulting solution. Some apparatus used for volumetric analysis These are burette, pipette, conical flask, beaker, funnel, wash bottle and volumetric flask. Standard solution is a solution of a known concentration. Basic Principles of Volumetric Analysis Test substance or analyte, is normally a base in acid-base titration, is pipetted into the conical flask. The burette contains