2.4 Measuring directly the specific heat capacity of a liquid like water

You can use a similar set-up to that described above for measuring the SHC of a solid block.

Instead of the block you can use a polystyrene cup (good insulation) with a lid.

Measure a mass of liquid into the polystyrene cup = mass of cup + liquid - mass of empty cup (measured on a mass balance).

You can use water for convenience.

Place the cup in an insulated box or beaker.

The double thermal insulation is essential to minimise the loss of heat energy to the surroundings.

Do extra diagram with a joulemeter?

The procedure is then identical to that described for a solid described in part 2.3.

In SHC experiments you can include in the power supply circuit a joulemeter to measure the energy transferred, which makes the calculation a lot easier.

By using a joulemeter you don't need the voltmeter and a ammeter, plus the extra calculation.

energy transferred = mass of water x specific heat capacity of water x temperature rise

energy transferred = ∆E (J) = m x c x ∆θ = mass of water (kg) x SHC_H2O (J/kg^oC) x ∆T

rearranging gives: SHC_H2O = ∆E / (mass of water x ∆T)

Let the temperature rise a good 10 degrees and repeat the experiment at least twice to get an average - for the most accurate result.

If you have no joulemeter, then, as in the diagram, take measurements from a voltmeter and ammeter.

The use the equation: total energy transferred

Energy (J) = P (W)  x t (s) = I x V x t = current (A) x p.d. (V) x time in seconds

Using SEARCH some initial results may be ad links you can ignore - look for docbrown

INDEX for my physics notes on specific heat capacity