Acid alkali dilution

[elgroucho]

What happens to the pH of an acid if you dilute it?

What happens to the pH of an alkali if you dilute it?

[foulecamp]

pH is defined as the neg log of the hydrogen ion concentration: if you dilute acid or alkali you reduce the H+ concentration and therefore bring both of them nearer to the pH of water, which is 7.

In brief: acid pH goes up, alkali pH comes down.

[AGENT X]

if you think in terms of volume diluting anything will bring the level of an internal componant down unless you do have a standard where you can bring it to a point of neutrality. example ph of the human body ranges from 7.35-7.45 thus being a standard. dilute the fluid in the body and the ph goes down making more alkalodic than acidotic. dehydrate the body and the tendancy is to go acidotic, but you also have to have that standard to what neutral is considered.

[Gef]

Correct answer from foule assuming it is diluted with pure water (ie ph = 7). No idea what AgentX is talking about/

[shammydodger]

Foulecamp and Gef are correct. Take it from a BSc in chemistry. What AgentX is saying, I'm not quite sure.

Unless, if you consider that going from pH 1 to pH2, for example, is going less acidic. Therefore, by definition, it is becoming more alkaline. Although most, if not all, chemists would be loathe to think of it in those terms until the pH was larger than 7.

Neutral pH IS 7. Not 7.35 or anything else. Biologists, as they are wont to do, will try to tell you otherwise. Don't believe them. Neutral pH is defined mathematically as 7. Above is alkaline, below is acidic. Disbelieve me at your peril, particularly if you are due to sit a GCSE or A level.