Question

what are the arrhenius definitions for an acid and base? give a chemical equation to demonstrate a strong acid and a weak acid

Answer 1

The Arrhenius definition of an

acid is a substance that when dissolved in water increases the concentration of hydrogen ion, H⁺_(aq).

A base is a substance that when added to water increases the concentration of hydroxide ion, OH^-_(aq).

Fairly simple definitions in appearance, yet are they? The first word that might give us some pause is 'increase', a word we recognize and use frequently in our own vocabulary, but how is it being used here? What is being increased? The definition says hydrogen ion or H⁺(aq). If a substance which increases the [H⁺] in water is an acid, in order for us to use this definition we have to be able to understand increase, how much H⁺(aq) is found in water before adding any compounds. So before we go any further lets spend sometime talking about water, which will aid us in our understanding of acid/base character.

If we consider pure water, H₂O, and measure its electrical conductivity, we see, to the limits of our measuring device, that it is a nonelectrolyte (there are no ions present). Electrical conductivity is a measure of the ability of a solution to carry an electrical current. Solutions of electrolytes conduct an electrical current by the migration of ions under the influence of an electrical field. A solution with a high concentration of ions will have a low resistance to current flow and will have a high conductivity. In fact if we had a device sensitive enough we do measure some conductance. What do we associate with causing the conductance? Ions. What ions? For water I'd like to suggest that the ions that cause the conductance are the following-