I am planning to investigate how long a candle burns for when put under a glass beaker. I am also aiming to see whether it is the candle or the size of the beaker that determines how long the candle burns for. I also want to find out if you can determine the volume of a gas jar, just by timing how long the candle burns for when placed underneath. Prediction/Hypothesis The burning of the candle is called combustion. This is the reaction of a substance with oxygen from the air. During combustion, the candle that burns is oxidised to produce oxides. Also, energy is given out in the form of heat, light and sometimes sound energy.

Any specific volume of air will only contain a limited and fixed percentage of oxygen gas molecules. I predict that the larger the beaker, the larger the volume of gas inside the beaker. Therefore, the more oxygen molecules in the beaker, which then means the longer the candle will be lit for, because the reaction will stop when the oxygen level drops too low. As combustion requires oxygen, it follows that the larger the beaker, the more oxygen will be available for the reaction, and the longer the reaction will last for. The oxygen is removed from the air during the reaction.

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The increase in volume of atmospheric gas will make more oxygen available for the reaction. The more oxygen that is available, the more that combustion can use. A fire needs three things to keep it going; fuel, oxygen and heat. Without these, a fire will go out. The flame of a candle needs the oxygen inside of the beaker to carry on burning. The more oxygen there is, the more the candle can use. The larger the beaker, the more oxygen that it contains. So, the larger the beaker, the longer the candle will burn for. Plan First of all we set up our apparatus.

Equipment Five different sized beakers 105cm cubed 282cm cubed  500cm cubed  600cm cubed  1100 cm cubed One Gas Jar with an unknown volume Six candles of exactly the same size Stop Watch Plasticene Measuring cylinder Safety mat Diagram of apparatus Method Firstly, I must clear away all un-needed equipment so we can make as much use of all available space as possible. In pairs, we must remember to block up all of the gaps in the beakers, with plasticene. We will find the actual air space of each beaker, by filling them by water and by using a measuring cylinder, measure how many ml of water each beaker can contain.

Then we will record our result into a Results table. The factors that I will change are the size of the glass beakers ONLY. Everything else will be kept the same. We are aiming to measure how long the candle burns for. To make my experiment safe, we will be wearing goggles throughout the whole experiment, and we will make as less mess as possible. We will also keep all bags/coats etc under the desk, and we will stand throughout the whole experiment. To make our experiment a fair test, the candles that we use, will be of the same wax, size and colour.