2007-03-12 12:14:37 · 17 answers · asked by violinmaster 1 in Science & Mathematics ➔ Chemistry
The pH of pure water is 7.
About 1 molecule of water, out of 10 million, breaks down into HO- and H+ ions. That's 1 in 10^7, which is where the 7 comes from.
2007-03-12 12:23:24 · answer #1 · answered by morningfoxnorth 6 · 0⤊ 0⤋
The answer is highly dependent on how you define "water" and where you got it.
If you have ultrapure water in a vacuum or under repeated purgings of a non-reactive gas like nitrogen, you can approach seven.
If you have that same water exposed to air, the pH can drop to 4.5 due to reaction with carbon dioxide from the air. You can not prevent this from happening in most cases, but the water will be highly unbuffered so the pH can be changed easily.
If you get water from any natural source such as a creek, lake, well, or even rain, it will be high variable in pH depending on location, weather, and even how you take the sample. It can be acid, down to pH 3 or it can be basic up to 9-10.
If you are talking tap water, that will also vary, depending on the season, due to different treatment regimes at the local utility. They do this because different seasons may require different treatments to remove all the impurities and bacteria.
Bottom line, "water", if you know nothing else about what the asker means, would have a pH of 7, since that is the theoretical value. In practice, it is hardly ever 7.
2007-03-13 09:42:24 · answer #2 · answered by Peter Boiter Woods 7 · 0⤊ 0⤋
7
2007-03-12 12:17:53 · answer #3 · answered by pentech_99 2 · 0⤊ 1⤋
7
2007-03-12 12:16:54 · answer #4 · answered by Anonymous · 0⤊ 1⤋
7
2007-03-12 12:16:52 · answer #5 · answered by John S 6 · 0⤊ 1⤋
pH 7 is defined as neutral because it is the pH of pure water at 25 °C.
2007-03-12 12:31:41 · answer #6 · answered by Barkley Hound 7 · 0⤊ 1⤋
7 because that is considered neutral between acidic and base on the Ph Scale
2007-03-12 12:18:24 · answer #7 · answered by Ezz 6 · 0⤊ 1⤋
Slightly below 7, carbon dioxide in the air mixes with the water forming carbonic acid.
2007-03-12 12:17:46 · answer #8 · answered by Vegan 7 · 1⤊ 0⤋
7 in natural water
2007-03-12 12:19:47 · answer #9 · answered by FoxHound 2 · 0⤊ 1⤋
Pure water has exactly 7 I think.
2007-03-12 12:17:38 · answer #10 · answered by Anonymous · 0⤊ 0⤋