Significant figures

It is important that we express the correct number of significant figures in our calculations. Take the example below.

Work through this sample calculation and post your answer:

In an experiment to determine the specific heat capacity of an oil, the hydrocarbon was:

Heated with an appliance rated 143W ± 1W (P)

The heater supplied energy for 634s ± 1s to the oil (t)

The initial temperature was 25.5 oC ± 0.5 oC and the final temperature was 47.5 o C ± 0.5 oC (T)

The oil had a mass of 581g ± 1g (m)

Calculate the specific heat capacity (c) of the oil using the equation:

c = Pt / m∆T

What value would you give for the uncertainty?

2 Comments
  • Jac
    March 24, 2010

    c=7.09 J/g/K
    uncertainty =+/- 0.40 J/g/K

    • David
      March 26, 2010

      Thanks Jac – I am assuming the calculation is correct… Sorry for the delay in replying, for some reason your reply went into the trash!

      I would argue that the final answer should be to 2sf and not 3. I made the temp change 22 oC – did you make it 22.0 oC?

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