Tiêu đề 12-Gases in the atmosphere-IGCSE(9-1)-Edexcel-Chemistry-Notes.pdf ✅

Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ 2.9: Know the approximate percentages by volume of the four most abundant gases in dry air The Composition of Air: The table below shows the approximate percentages by volume of the main gases in unpolluted, dry air: Gas Percentage In Air Nitrogen 78 % Oxygen 21 % Argon 0.9 % Carbon Dioxide 0.04 %
Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ 2.10: Understand how to determine the percentage by volume of oxygen in air using experiments involving the reactions of Metals (E.g. Iron) and non-metals (E.g. Phosphorus) with Air Determining Percentage Volume of Oxygen in Air using Metals: Percentage Volume Of Oxygen In Air - Using Metals Diagram Showing the Use of Iron to Calculate Percentage Volume of Oxygen in Air Method: ● Place wet iron fillings at the end of a burette (use vaseline if iron filings do not stick) ● Use a clamp to hold the burette vertically in the trough of water ● Measure and note the starting height of the water level in the burette ● Leave apparatus for weeks ● Measure and note the final height of the water level in the burette Results: ● After several days, the water will rise up the burette and reach a constant level as the iron filings will react with all the oxygen in the air to form iron (ii) Oxide (rust). ● The water level will rise to replace the volume of Oxygen lost during this reaction ● E.g. the original water levels was 15 cm2 and is now 12 cm2 . 3 cm2 has been used up. 3/15 x 100 = 20% Oxygen in air