A candle is made of wax. Candle wax is a fuel. It contains the elements carbon and hydrogen. Part 1: A candle is placed on a heatproof mat. The candle is then lit. A beaker is placed over the candle.
Part 2: Three candles of different lengths are placed on a heatproof mat. The candles are lit. A beaker is placed over the candles.
Part 3: A floating candle is placed in a basin of water. The candle is lit. A beaker is placed over the candle and on top of the water.
For each investigation: a. Predict what will happen.
b. Set up and carry out the investigation.
c. Explain your observations. z Fig. 14.1.2 Investigation 1 Investigating the products of combustion
When hydrocarbons are burned, carbon dioxide and water vapour are produced. The word equation for the combustion of hydrocarbons is as follows:
Fuel (hydrocarbon) + oxygen → carbon dioxide + water 1. Name the reactants and the products in the above reaction.
2. Plan, design, carry out and write up an investigation to show that the products of combustion are carbon dioxide and water.
3. What safety precautions did you take during this investigation? Oxygen in Air
Learn more about the composition of air in Earth and Space 22.4
z 238 Fig. 14.1.3
Measuring the percentage of oxygen in air
Air is made up of around 21 per cent oxygen gas. The investigation shown in Fig. 14.1.3 is used to show this. Copper turnings are heated using a Bunsen burner. As the copper is heated, air is passed over it by pressing on syringes. This causes a reaction between the copper and the oxygen in the air to form copper oxide.
