The pH of a substance is a measure of its acidity or basicity. The lower the pH, the more acidic the substance is. The pH scale ranges from 0 to 14, with 7 being neutral (neither acidic nor basic), and numbers below 7 indicating increasing acidity.
The relationship between pH and hydrogen ion concentration is given by the formula:
pH = -log[H+],
where [H+] is the hydrogen ion concentration in moles per liter (mol/L).
Distilled water has a pH of about 7, which means that its hydrogen ion concentration is [H+] = 10^(-7) mol/L.
The tap water in this question has a pH of 6.3. To find its hydrogen ion concentration, we can use the formula above:
6.3 = -log[H+]
[H+] = 10^(-6.3) mol/L
The tap water is more acidic than distilled water by a factor of:
[H+]_tap / [H+]_distilled = 10^(-6.3) / 10^(-7) = 10^(0.7) ≈ 5.0
Therefore, the tap water is about 5 times more acidic than distilled water in terms of their hydrogen ion concentrations.