A solution has a pH of 7.0.  What would happen to the pH if H⁺ ions were added?

The correct answer is: pH would decrease

• From 0.1 to 10-14, this scale covers a fairly wide range of [H+]. We typically use [H+] instead of the pH value when [H+] is high. For instance, pH is zero when [H+]=1.0.
• The H+ stands for acids, and if the acid is added to the neutral solution, it becomes acidic and the pH gets down.
• Because we don't often use the expression pH = 0, you could find it strange. An [H+] of 2.0 M is the same as a pH of -0.30. Only academic exercises can have a pH value that is negative. Instead of using the pH scales, directly using concentrations makes more sense.
• Since the pH scale uses the negative log of [H+], it typically has positive values. Furthermore, [H+] decreases when pH increases.