Question

A student who did the same experiment that you did determined the specific heat for all of the metals. His values were all 0.10 to 0.20 less than the actual specific heat values. Select all possible sources of this error listed below.

The metals were not heated to 100°C.

The metals were heated beyond 100°C.

The metals cooled before they were added to the water.

The thermometer was not completely submerged in the water while reading.

The calorimeter was not sealed properly, so heat escaped.

Less metal was added to the calorimeter than was massed.

Answer 1

Possible sources of a systematic underestimation of the metals' specific heats (0.10–0.20 too low):

- The metals were not heated to 100°C.
(If the student assumed the metal was 100°C but it actually was cooler, the used ΔT for the metal is too large and the computed c is too small.)

- The metals cooled before they were added to the water.
(Same effect as above: initial metal temperature is lower than assumed, giving a too-large denominator and a low calculated c.)

- The thermometer was not completely submerged in the water while reading.
(If the thermometer reads a too-low equilibrium temperature, the calculated heat gained by the water is too small and ΔTmetal is artificially large → c too small.)

- The calorimeter was not sealed properly, so heat escaped.
(Some heat is lost to the surroundings instead of warming the water, so the measured temperature rise is too small → calculated c too small.)

- Less metal was added to the calorimeter than was massed.
(Using a larger mass in the calculation than was actually present makes the denominator too large, so the computed c is too small.)

Not a likely cause of uniformly lower values:

- The metals were heated beyond 100°C.
(This would generally lead to the opposite sign of error if the student assumed 100°C, or is unlikely if metals were boiled in water; it does not explain a consistent underestimation in the usual boiling-water calorimetry setup.)