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. Our experiment will be repeated three times, and we will use the same stopwatch.
We will place the candle onto the safety mat and light it. Carefully, one of us will cover the lit candle with the beaker, whilst the other shall start the stopwatch. As soon as the candle goes out the stopwatch shall be stopped, measured and the result will be recorded into the results table. This shall be repeated two more times for the same beaker and the results will also be recorded into the results table.
We will carry out this method four more times for the measured beakers, and then we will do the same with the Gas Jar.
The difference in method between the Gas Jar and the other beakers is that we know the volumes of the other beakers, but the volume of the Gas Jar is unknown.
For the Gas Jar, we will put a candle onto a safety mat, light it, and then cover it with the Gas Jar. We will start the stopwatch and record how many seconds the candle is lit for. As soon as the candle goes out, the stopwatch will be stopped. We will record the amount of time the candle is lit for, into the results table.
Then I will find the average result of the three tests for each beaker. I will find this by using this formula.
This average will then be recorded into my results table.
Then I will draw my graph.
On my graph, the seconds will be on the “y” axis and the volumes of the beakers will be on the “x” axis. I will plot all of my results onto my graph and measure a line of best fit. On the line of best fit will be all of the approximate results of the seconds the candle is lit for, for all volumes of beakers.
To find the volume of the gas jar, I will plot the time that the candle was lit for on the line of best fit. Then I will follow my finger from the line, horizontally, to the “y” axis, and see what the approximate volume of the Gas Jar is.
Results
Analysis
From my results I have found out the Gas Jar has an approximate volume of 200 cm cubed. I conclude that it is possible to find out the volume of a beaker when all you know is how long a candle burns for when it is placed underneath.
The graph proves my prediction to be correct. I said that the larger the beaker, the longer the candle will burn for, which would then give my graph a positive correlation. This is what happened. When the size of the beaker went up, so did the amount of time the candle beneath it.
There was a relationship between the variables I was measuring – The larger the Beaker, the longer the candle will burn for.
I proved that there is more oxygen in a large beaker than a small beaker, as the small beakers candle did not stay lit for as long as a larger beakers candle.
Evaluation
I have achieved the aim that I wrote at the beginning of my experiment. I have found out whether it is the candle or the size of the beaker that determines how long the candle burns for. I have also found out that you can determine the volume of a gas jar, just by timing how long the candle burns for when placed underneath.
My plan was quite good. I have achieved all that I wanted to achieve, and found out all that I wanted to find out. I have gained everything from my experiment that I had aimed to gain, and without any problems.
I don’t think that I could have changed anything to make it better, except to maybe do more tests to get my average from, because they will, of course, be more accurate.
I didn’t change anything to make anything work better, it already worked perfectly fine.
My results were very good, all of my results were consistent as they were quite close to each other. Also they followed my prediction perfectly, I had no problems.
From my results I have calculated that the Gas Jar had an approximate volume of 200 cm cubed.
The actual volume of the gas jar is 210 cm cubed. This result is extremely close to my approximation, which means that my results were very accurate. I also believe that my experiment was a very fair test, we followed our method exactly and had no reason to change anything.
I think that my results were pretty reliable. There was an obvious line of best fit in which many of the results fitted in with. I did have one anomalous reading though, but it was not far off track. An Anomalous reading is a reading that didn’t follow the same pattern as the others.
This might have occurred because of a number of reasons. For example, We could’ve made an error in taking measurements or we might not have filled up the gaps in the beaker enough etc.
I think, that by carrying out a further experiment, we would extend our knowledge by changing the experiment a little, by maybe changing a different variable or by having more tests. Either way, we would learn a lot more on this specific subject.
Katrina Farrant 10HA