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Quantitative Investigation · Part 3 of 3
6 exam-style questions with model answers, plus 8 quick multi-choice questions — every question on this part of the standard, grouped by the 2 pages of notes they come from.
Write a full answer before you reveal the model one. That comparison is where the learning happens.
A student's titres for one sample are 21.40, 20.85, 20.90 and 20.80 mL. Identify the concordant titres, calculate the mean, and explain why the first value is excluded.
Explain how a conclusion for this standard should be written so that it links the processed data to the purpose, and illustrate with an example.
A student's five data points show a clear downward trend, but one point sits 25% above the line. Evaluate how this should be handled in the report, and justify your recommendation.
Describe two possible sources of error in a titration-based investigation and state the direction each would bias the result.
Explain the difference between the precision and the validity of a set of results, and explain why a set of highly precise results can still fail to support a conclusion.
A student's evaluation reads: "There may have been human error. The results could be improved by repeating the experiment more times and being more careful." Evaluate this against the Excellence criterion and justify what a comprehensive evaluation would contain instead.