percentage errors in as ocr chemistry

To calculate the percentage error, you take the error marked on the equipment, e.g. +/- 0.1ml, and divide this by whatever your measurement was, e.g. 25ml, then multiply all of this by 100 to get it as a percentage, so in this case, the percentage error would be 0.4%.

If you have taken more than one measurement, for example when calculating a change in temperature, then you multiply the error given (e.g. +/- 0.1 degrees), by the number of measurements that you have taken, and use the difference between them.

For example, you are measuring the temperature change of some water (maybe you're calculating specific heat capacity or something), and the temperature rises from 18 degrees to 31 degrees. Your thermometer has marks for every degree, so its error is +/- 0.5 degrees. You have taken two measurements, so the error is doubled, to +/- 1.0. Your temperature change (31-18) is 13 degrees, so you calculate (1.0/13)x100 = 7.69%

Remember, the smaller the measurement you are taking, the larger the percentage error, so increasing sample size will reduce the error (as well as using equipment with a smaller error).

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