What should the pH of salt water be?

1 Answer
Feb 9, 2017

Answer:

Of aqueous sodium chloride? #pH=7#.

Explanation:

Sodium chloride is the salt of a strong base, #NaOH#, and a strong acid, #HCl#. Because this is a strong base/strong acid pair, by definition, their counterions, #Na^+#, and #Cl^-#, do not undergo water hydrolysis. Contrast this behaviour with an aqueous solution of #"sodium fluoride"#. The #pH# of this solution is #>7#. Given that #HF(aq)#, unlike #HCl, HBr, HI#, is a WEAK ACID, how can this solution behaviour be rationalized?