BRAINCAKEUncertainty
Because every measurement has some error, a measured value is really a range. The uncertainty gives the size of that range: it is the amount either side of the reading within which the true value is expected to lie. It is written with a ± sign, for example 25.0 ± 0.1 cm3.
The uncertainty depends on the apparatus used.
• Scales read by eye (thermometer, burette, measuring cylinder): the uncertainty of a single reading is normally half the smallest division. A thermometer marked every 1 °C gives ± 0.5 °C, and a burette marked every 0.1 cm3 gives ± 0.05 cm3.
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Key terms in this lesson
- tolerance
- The manufacturer's stated uncertainty of a piece of volumetric glassware, such as a pipette or volumetric flask.
More in Errors and Uncertainties
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- Random Errors and Systematic Errors
- Percentage Uncertainty
- Adding Uncertainties
- Adding Percentage Uncertainties
- Minimising Errors and Uncertainties
- Percentage Yield
All 14 lessons in Errors and Uncertainties · All Edexcel AS-level Chemistry topics