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:

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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 does not stick) Use a clamp to hold the burette vertically in the trough of Water Measure and note the starting height of Water level in the burette Leave apparatus for several days Measure and note the final height of Water level in the burette

RESULTS: As the Water level will rise to replace the volume of Oxygen lost during reaction to form Iron (II) Oxide, a constant Water level will be reached as Iron fillings will fully oxidise with Oxygen in the air

CALCULATIONS: Volume of Air at the Start = ( Total Burette Volume - Initial Burette Reading) Volume of Oxygen Used (Reacted with Iron) = ( Initial Reading - Final Reading ) Percentage Volume of Oxygen Calculation:

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DETERMINING PERCENTAGE VOLUME OF OXYGEN IN AIR USING NON - METALS:

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PERCENTAGE VOLUME OF OXYGEN IN AIR - USING NON - METALS

Diagram showing the Use of Phosphorus to Calculate Percentage Volume of Oxygen in Air

METHOD: Add Phosphorus into an evaporating dish and place it on a trough of Water Ignite Phosphorus using a candle Cover evaporating dish with a bell jar Measure and note the starting height of the Water level in the bell jar Leave apparatus for several days Measure and note the final height of the Water level in the bell jar

RESULTS: As the Water level will rise to replace the volume of Oxygen lost during this reaction, a constant level will be reached as Phosphorus will use up all Oxygen in Air to burn (Oxygen is one of three Elements that a fire needs)