# Uncertainties in measurements: chemistry

I can explain why there is some uncertainty when measurements are made, how to minimise uncertainty, and calculate uncertainties.

# Uncertainties in measurements: chemistry

I can explain why there is some uncertainty when measurements are made, how to minimise uncertainty, and calculate uncertainties.

## Lesson details

### Key learning 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.
- 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.

### Common misconception

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

Highlight that equipment with smaller resolution provides more precise measurements, which can decrease the uncertainty of a calculated mean.

### Keywords

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.

### Licence

This content is Â© Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Video

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## Starter quiz

### 6 Questions

An error that has an equal probability of being too high or too low.

The closeness of two or more measurements to each other.

The degree to which a measurement reflects the true value.

A variable that is kept constant throughout an experiment.

## Exit quiz

### 6 Questions

Quantitative information about an object or system.

The range within which the true value can be found.

An average calculated from a set of values.

The smallest change a piece of apparatus can measure.

A piece of equipment designed for a particular use.