How do acids and alkalis react?
This experiment provides important evidence for the simple hydrogen ion theory of acidity, and for the ionic nature of the neutralisation reaction with hydroxide ions. Thus it forms a natural part of a sequence of experiments in which this theoretical model can be built up for students. This experiment is not likely to be useful on its own. It also depends on students’ understanding of ionic theory in general, and their appreciation that the conductivity of a solution depends on the concentration of ions in the solution. Alternating current is used rather than direct current to avoid electrolysis taking place, at least to any extent that would affect the outcome of the experiment. Although this is likely to be a demonstration for most students, some teachers may wish to use it as a class experiment, possibly with older students. Safety issues are relatively minor, essentially using dilute sulfuric acid (1.0 mol dm-3) and barium hydroxide solution (0.1 mol dm-3). The latter should be tr
