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SALTERS ADVANCED LEVEL CHEMISTRY

Scribble on Error analysis in Activities EL 1.1 and EL 2.1

Return to My Salters AS homepage - "Unit EL Elements of Life"

My Salters AS page * My Salters A2 page * My Salters Index

• basically the % error is calculated as follows:

  • the 'error for that apparatus' x 100 / effective reading

• there is guidance in the activities as to what the error is acknowledged to be

  • generally it is taken to be ¹/₂ of the smallest unit on the scale being used

  •  eg if a balance weighs to 0.01g the error uncertainty is taken as 0.005g

• In the case of EL1.1 there are three weighing errors to be added together.

  • BUT make sure you use the 'effective' results eg actual mass of copper etc.

  • NOT the original recorded weighings, eg if you did the experiment in a test tube + Xg Cu = 15g total, and somebody else did it in a pyrex boiling tube + Xg Cu = 30g total

  • the weighing error for 2dp balance is 0.005 x 100 / X

  • NOT 0.005 x 100 / 15 or 30, using a heavier pyrex tube will NOT halve the weighing error!

GENERAL REVISION NOTES

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