11.1 Uncertainties and Errors in Measurement and Results

Which of the following best describes a systematic error?

A. An error that occurs unpredictably and without a consistent pattern.

B. An error that arises due to faulty equipment or incorrect calibration.

C. An error that can be reduced by taking multiple measurements.

D. An error that arises due to the limitations of human observation.

What is the primary difference between accuracy and precision?

A. Accuracy refers to how close a measurement is to the true value, while precision refers to how close repeated measurements are to each other.

B. Accuracy refers to how close repeated measurements are to each other, while precision refers to how close a measurement is to the true value.

C. Accuracy and precision both refer to how close a measurement is to the true value.

D. Accuracy and precision both refer to how close repeated measurements are to each other.

Which of the following is a common source of random error?

A. Faulty equipment

B. Incorrect calibration of an instrument

C. Fluctuations in experimental conditions

D. Biased data recording

If the absolute uncertainty in a measurement is 0.5 and the measurement itself is 10, what is the relative uncertainty?

A. 0.05

B. 0.005

C. 5%

D. 50%

When adding or subtracting quantities, how is the absolute uncertainty determined?

A. By adding the absolute uncertainties of the quantities.

B. By subtracting the absolute uncertainties of the quantities.

C. By multiplying the absolute uncertainties of the quantities.

D. By dividing the absolute uncertainties of the quantities.

a) Define systematic errors and provide an example of a cause for such an error in a chemistry experiment. [2]

b) Explain how systematic errors can be corrected in experiments. [2]

a) Differentiate between accuracy and precision in the context of experimental measurements. [2]

b) If a student repeats an experiment five times and gets values very close to each other but far from the accepted value, is the student's data accurate, precise, or both? Justify your answer. [2]

a) What is meant by absolute uncertainty in the context of experimental measurements? [2]

b) A student measures the volume of a liquid as 50.0 ± 0.5 mL. What is the relative uncertainty of this measurement? [2]

a) Describe the main causes of random errors in a chemistry experiment. [2]

b) How can random errors be minimised in experimental measurements? [2]

c) If a student repeats an experiment multiple times and observes varying results, what type of error is likely responsible? [2]

a) Explain the difference between absolute and relative uncertainty. [3]

b) A student measures the mass of a sample as 20.0 ± 0.2 g. Calculate the relative uncertainty of this measurement. [2]

c) Why is it important to consider relative uncertainty when comparing results from different experiments? [2]