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
Paper 1 1. All your burette reading (initial and final) as well as size of the pipette must be recorded, but no experimental procedure is required. All calculations must be done on this question paper. A is a solution containing 0.15moldm -3 HNO 3 . B is a solution containing 4.20gdm -3 of X 2 CO 3 salt. Put A into the burette and titrate against 20cm 3 or 25cm 3 portion of B using methyl orange as an indicator. Repeat the titration three more times and record your results in the table below. Volume of pipette used ……….cm 3 Titration Rough 1 2 3 Final burette reading(cm 3 ) Initial burette reading (cm 3 ) Volume of A used(cm 3 ) (6 marks) a) Calculate t