Zadanie 1a
Identify the independent variable and the dependent variable in this investigation.
- Materiał graficzny
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Dodaj cały arkusz do zestawuIdentify the independent variable and the dependent variable in this investigation.
State two variables that should have been kept constant in the four runs.
Discuss the range of the independent variable and the quantity of data in this investigation.
Suggest why the light intensity rose during the first minutes of each run.
Suggest how the total quantity of light emitted in each run could be obtained from the graph.
Explain how the rate at which the light intensity was falling after 15 minutes in the 44.8 °C run could be determined from the graph.
The graph shows the maximum rate of decrease in light intensity for each run, plotted against temperature. (i) Draw the best-fit curve on the graph. (ii) Suggest two possible conclusions that can be drawn from the investigation.
Suggest two modifications to the procedure that would make the data more reliable.
Calculate the change in temperature for trial 5 and its uncertainty. Give the temperature change to a suitable number of decimal places and the uncertainty to a suitable number of significant figures.
The student decided to ignore the uncertainty in the mass of ethanol burnt when calculating the specific energy. Discuss whether this decision is valid, using the percentage uncertainties for trial 5.
Calculate the specific energy of ethanol for trial 5, in J g−1. Use sections 1 and 2 of the data booklet. mwater = 120.0 g
Determine the mean specific energy of ethanol from the five trials, explaining your method. If you did not obtain an answer to (c), use 8000 J g−1 for trial 5; this is not the correct value.
Calculate the percentage error in the mean specific energy of ethanol. Literature value of the specific energy of ethanol = 29.7 kJ g−1
Suggest two ways in which the error in this experiment could be reduced.