As a model of the new system a prototype allows for several forms of communication. First, it allows the developers to communicate to the users their understanding of the requirements. (Obviously before a prototype can be built there must be some initial requirements discussions between developers and users).
(Arrhenius) a substance that yeilds hydroxide ions in an aqueous solution; metallic oxides in water. Buffers. substances that in solution are capable of neutralizing, within limits both acids and bases, and thereby maintaining the original or constant pH of the solution; substances that prevent changes in pH. Ex. borax, sodium phosphates, and citrates. Crystallization. the process by which a substance is given definite form.
In pure water, there are an equal number of hydrogen ions and hydroxide ions. The solution is neither acidic or basic. An acid is a substance that donates hydrogen ions. Because of this, when an acid is dissolved in water, the balance between hydrogen ions and hydroxide ions is shifted.Now there are more hydrogen ions than hydroxide ions in the solution. This kind of solution is acidic.A base is a substance that accepts hydrogen ions.o be more precise, pH is the negative logarithm of the hydrogen ion concentration: pH = âlog [H+]. The square brackets around the H + automatically mean concentration to a chemist. What the equation means is just what we said before: for each 1-unit change in pH, the hydrogen ion concentration changes ten-fold.