Why is it possible to drink a solution that contains equal concentration of a strong acid and a strong base?

Answer 1

WWhy is it possible for us to drink a solution that contains a mixture of equal concentration of a strong acid and a strong base, either of which, separately, would be very caustic?

While I personally would let the solution sit for awhile and then stir it before consuming, it would be possible to drink a solution that has equal concentrations of a strong acid and a strong base because a strong acid and a strong base would form a salt and water (both of which are neutral in pH!)

Here is a reaction of a strong acid and a strong base:

HCl (aq) + NaOH(aq) --> NaCl(aq) + HOH(l)

Hydrochloric acid and Sodium hydroxide --> Sodium chloride (table salt) and Water. This is not a very reversible reaction, therefore it would be pretty safe to assume that the mixture would not revert back to its reactants.

Answer 2

Acids and bases, like all matter, contain energy. When a strong acid and a strong base are combined, they form water (H+ + OH- -> H2O). Water is much more stable than the original acids and bases and because of that, we say it is in a lower energy state. If you ever take a statistical thermodynamics course in a University, you will be taught why this is true. Until then, accept the fact that it is.

So when water is produced, the excess energy needs to be released. (Because water has a lower energy, remember?) This comes off as heat, which we denote q.

When you divide q, the heat, by the number of moles present, you get dH (delta H), or the Enthalpy (or heat) of neutralization.

So the base and the acid are equal. They both contribute the same amount of moles to the neutralization, and therefore both provide the same energy difference.