1. Beaker Size & Candle Burning Time
Scientific Enquiry Question

2. The diagram shows a candle burning in air under a bell-jar.
You need to plan an investigation to find out if there was a relationship between volume of the container and burning time. You will use 600mL, 400mL, 200mL, 100 mL and 50 mL beakers.

3. The pupils set up an inverted (upside down) beaker over a
candle . They lit the candle
and quickly, but carefully, put
the beaker over the top of it and
timed how long it took for the
flame to go out. This was
repeated 3 times for each
beaker.
(b) The results from one group of pupils are given below.
(i) Calculate their average burning times. Put the answers in the table
Beaker
volume (ml)
Burning Times (secs)
Average
Burning
Time 50
2.1
1.9
2.0
100
4.8
5.1
200
7.3
7.7
7.5
400
12.8
13.0
13.2
600
18.1
17.8
18.7

4. (ii) In this experiment each part of the experiment was repeated 3 times. Why is it often a good idea to repeat the readings?
____________________________________
(c) Plot a graph to show the results.
The graph must have title that makes it clear what has been done.
The axes must be labeled to show the dependent and independent variables.
Any suspect or odd points must be made clear. (if there are any)
A best-fit line should be drawn.
Attach your graph paper to this sheet

5. Graph of beaker volume versus average burning time
for a candle X X
Average burning time (s) X X
Beaker volume (ml)

6. (d) Describe the relationship (or pattern) you can see in the graph.
_____________________________________
(d) Use the graph to help you answer the next section of questions.
What burning times would you expect in the following beakers?
(i) 500 ml ________ (ii) 50 ml _______ (iii) 800 ml ________

7. (e) Explain why you would be more confident about the answer you gave for the 500 ml beakers than the answers for the 50 and 800 ml beakers.
(f) It looks as if the results were quite reliable overall and so the strength of evidence for the conclusion could be fairly strong. However, no experiment is likely to be perfect. Go back and look at the diagram and the brief method again.
Point out possible sources of error in this experiment.