2 Using Sandra’s diagram, write up a list of equipment that the students would need to carry out the investigation.
3 Using Sandra’s diagram, write up a step-by-step method that the students would follow during this investigation.
4 What safety precautions should the students take during this investigation? 5 What did the students do to make sure that this was a fair investigation?
Sandra and Breda discussed the range of temperatures they would use. Breda felt that cold acid and warm and hot solutions of the sodium thiosulfate would be enough to test the hypothesis. Sandra did not agree – she felt that Breda’s suggestion would only allow them to draw a bar graph of their results.
6 Why would Breda’s suggestion have to be drawn on a bar graph?
7 Why would the choices given by Breda not allow the students to test the hypothesis?
After discussing their options, Breda and Sandra decided to use the following temperatures: 20 °C, 40 °C, 60 °C, 80 °C and 100 °C. However, their teacher had safety concerns about the range of temperature values they were going to use.
8 What safety concerns do you think their teacher had?
Before starting their measurements, Sandra and Breda drew up a results table. 9 Draw a blank results table for this investigation.
10 Gather the equipment needed for this investigation and use the steps you developed in question 3 to carry out this investigation in your own school laboratory. Use your results table from question 9 to record your results.
11 Present the results of your investigation in a graph. What type of graph will you use? Why did you choose this type of graph?
12 Write up a conclusion for your investigation. Link the conclusion to the hypothesis at the start of this investigation.
