Question

Consider substituting a glass beaker for the polystyrene cup as the calorimeter when doing the experiment described in this laboratory.(a) Would you expect the calorimeter constant of the cup to be larger, smaller, or the same as that of the beaker? Briefly explain.(b) Would you expect the ∆Hneut to be larger, smaller, or the same when using the beaker instead of the cup? Briefly explain.

Answer 1

a. Glass has significantly higher thermal conductivity than polystyrene cup. Hence, for the same amount of heat, glass container will end up leaking more heat to the surrounding. Therefore, for a given amount of heat, a calorimeter made of glass would result in lower increase in temperature when compared to polystyrene. Calorimeter is defined as C_cal = ΔH/ΔT. Therefore, a glass beaker would have higher C_cal value compared to polystyrene cup.

b. ΔH_neut is dependent on the specific reaction (Acid-base) being carried out and is independent of the heat capacity of the container, therefore, a glass beaker would have same ΔHneut as with polystyrene cup.