Measuring Mass
Chemistry: AQA GCSE Higher, topic 3.1.6
Chemical Measurements
Every chemical measurement involves some uncertainty.
Uncertainty
- E.g. a digital thermometer is able to measure to a precision of 0.1oC.
- If this thermometer displayed a reading of 35.4oC, the actual temperature could be anywhere between 35.35oC and 35.45oC.
Reducing uncertainty
- The larger the uncertainty, the larger the range of results you should expect.
- This is a reason why it is important to repeat the measurements from experiments several times, and calculate an average from them.
Test yourself on Measuring Mass
If a digital thermometer can measure to a precision of 0.1°C, what is the range of temperatures that a 45.4°C reading can actually be?
A student compares two thermometers used to measure the same sample. Thermometer X has an uncertainty of 0.1°C and Thermometer Y has an uncertainty of 0.5°C. Which thermometer would give the wider range of possible actual temperatures for the same displayed reading?
Why is it useful to repeat a measurement several times and calculate an average, when every reading has some uncertainty?
A thermometer scale is marked in relatively large intervals. Why might the same recorded reading of 35.4°C actually represent a range of different real temperatures?
A thermometer reading of 35.4°C is rounded to the nearest marking on a scale. State the two more precise readings this could actually represent on a finer scale.