Effect of dilution on the pH value

By the end of this video, you should understand that pH provides a measure of the concentration of Hydrogen ions in aqueous solution.

Because pH is a measure of the hydrogen ion concentration, the pH value is independent of the volume of the solution measured. e.g. 10 cm3 of a 0.010 mol dm-3 solution of hydrochloric acid will have exactly the same pH as 1000 cm3 of a 0.010 mol dm-3 solution of hydrochloric acid.

However, if an acidic solution is diluted by adding distilled water, then the hydrogen ion concentration will change and so will the pH value.

The pH scale is logarithmic, meaning each whole pH value below 7 is ten times more acidic than the next higher value. For example, pH 3 is ten times more acidic than pH 4 and 100 times more acidic than pH 5.

The same is true for pH values above 7. Each value is ten times more alkaline than the next lower whole value. For example, pH 9 is ten times more alkaline than pH 8 and 100 times more alkaline than pH 7

Question: If 99.0 cm3 of distilled water are added to 1.0 cm3 of a solution with a pH of 2, what is the pH of the new solution?
Answer: The solution has been diluted by a factor of 100 and the diluted solution will have a pH of 4.

[rickrolls]

The first part is a no brainer, but by the end it was good info.

[mayzilber]

Thank you for the video! What will happen to the ph if we dilute even more…lets say by Would the ph ever rises than 7, and become a bace?

[tej_s]

If we take a cleaning chemical which has pH of 7 or close and dilute it for cleaning purposes, how will that impact its pH? Will it change or stay at 7?

[TheOtherGuybo]

If only this were true.
pH does not follow concentration, except in the extremes - it's way more complicated than that.