What is produced when a base is dissolved in water?

1 Answer
anor277
Jun 19, 2018

#"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....

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