Here's where things get fun. Just like the number of reps, 3-6 sets is the best range of volume for this training method. If you like your workouts paced like clockwork, take 30-60 seconds rest between each exercise.
The natural attraction between positive and negative keeps the ions surrounded by water molecules and therefore dissolved in solution. Many biochemicals are either polar molecules or charged ions (or both) so water makes an excellent solvent for them.
As a result, water is an excellent solvent for other polar molecules, particularly those which have hydrogen bonded to either oxygen or nitrogen atoms. This is because it is possible to have hydrogen bonding between the molecules. Water is also an excellent solvent for both positive and negatively charged ions.