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Year 10 - Science

Uncertainties in measurements: chemistry

Calculations involving masses

Unit Summary

This unit covers writing chemical formulae, balancing equations, and using the conservation of mass. It includes calculating moles, empirical formulae, relative formula masses, and theoretical yields. Emphasis is on stoichiometry, concentration, gas volumes, and using standard form.

Lesson Summary

You will learn to explain why there is some uncertainty when measurements are made, how to minimise uncertainty, and calculate uncertainties.

Key Notes

  • Whenever a measurement is made, there is always some uncertainty about the result obtained.
  • The uncertainty of an individual measurement is equal to half the resolution of the device used to take the measurement.
  • The higher the resolution, the lower the uncertainty of an individual measurement.
  • Half the range of repeated measurements equals the uncertainty of a mean value.
  • The uncertainty of a measurement provides a range within which the actual value can be found.

Vocabulary To Learn

  • uncertainty: is the range of measurements within which the true value can be expected to be found. On apparatus, it is half the value of one resolution marking.
  • measurement: provides quantitative information about an object or system.
  • mean: is an average calculated by adding up the values of a set of measurements and dividing by the number of measurements in the set.
  • resolution: is the smallest change a piece of apparatus can measure - shown by its markings.
  • apparatus: a piece of equipment that is designed for a particular use.

Common Mistakes To Avoid

  • Pupils rarely consider the choice of equipment and its link to the accuracy of the data they collect in a practical.

3 Quick Questions (With Answers)

1. Explain the scientific idea in this lesson using two key points.

Whenever a measurement is made, there is always some uncertainty about the result obtained. The uncertainty of an individual measurement is equal to half the resolution of the device used to take the measurement.

2. Define this scientific word and use it in context. 'uncertainty'

is the range of measurements within which the true value can be expected to be found. On apparatus, it is half the value of one resolution marking. Include the word in a full scientific explanation, not as a single label.

3. Correct this common scientific misunderstanding.

Mistake: Pupils rarely consider the choice of equipment and its link to the accuracy of the data they collect in a practical. Correction: Highlight that equipment with smaller resolution provides more precise measurements, which can decrease the uncertainty of a calculated mean.

More Lessons In This Unit

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