wrote in message
oups.com...
Jeff Rigby wrote:

Not that weak. If you take a distilled water and left it open pH goes
down from 7 to about 5.7 - just because of the presence of dissolved
carbon dioxide.

PH changes from 7, in other words from 5-9 in distilled water take very
little acid or base, in other words it's a very weak acid or base.

Remember that this change takes place in the presence of only about 380
ppmv of CO2 in the air. Increase amount of CO2 in the atmosphere and
the change will be higher. That doesn't mean carbonic acid is not a
weak one, you just don't need a strong acid to change pH when you have
solution close to pH 7.

Borek
--
http://www.chembuddy.com
http://www.ph-meter.info

That's like saying water is a solvent and it dissolves most compounds
because the hydrogen and oxygen molecule's geometry lends itself to tearing
apart most compounds. We should be concerned with water too. In fact it's
not the carbon dioxide that creates the acid, it's water. Without water
carbon dioxide is not an acid.

I'm not disagreeing with your comments, I find them VERY enlightening.
Following is typical household chemicals and their Ph ranking:

1 Stomach Fluids
2 Lemon Juice
3 Vinegar
4 Tomatoes
5 Coffee
6 Milk
7 Pure Water
8 Blood
9 Baking Soda
10 Borax
11 Rolaids, Tums
12 Household Ammonia
13 Bleach
14 Lye