Question

What is produced when a base is dissolved in water?

Answer 1

`"Hydroxide ions...?"`

Explanation:

We know that water undergoes a measurable autoprotolysis...i.e.

`2H_2O(l) rightleftharpoonsH_3O^+ + HO^-`

For which under standard conditions of `298*K`, and `100*kPa`..

`K_w=10^-14-=[HO^-][H_3O^+]`

And using standard logarithmic terms... `14=pH+pOH`, where `pH=-log_10[H_3O^+]`, and `pOH=-log_10[HO^-]`

Of course, when we add a soluble hydroxide to solution, for instance `KOH(s)` or `NaOH(s)` WE INCREASE `[HO^-]`...and increase `pH` BUT NUMERICALLY DECREASE `pOH`...

We COULD add a base such as ammonia, which undergoes an equilibrium reaction with water...

`NH_3(aq) +H_2O(l) rightleftharpoons NH_4^+ + HO^-`

Here, since the reaction is NOT quantitative, and governed by an equilibrium constant, `K_b`, significant concentration of ammonia will remain in solution....`pH` will be elevated above `7` due to the presence of SOME `HO^-` ions....