# What makes something acidic/alkaline?

**URL:** <https://boards.straightdope.com/t/what-makes-something-acidic-alkaline/262250>\
**Category:** Factual Questions\
**Created:** [August 30, 2004, 3:57pm UTC](https://boards.straightdope.com/t/what-makes-something-acidic-alkaline/262250 "2004-08-30T15:57:27Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Ortonia](https://avatars.discourse-cdn.com/v4/letter/o/a4c791/32.png) [@Ortonia](https://boards.straightdope.com/u/Ortonia)\
**Post date:** [August 30, 2004, 3:57pm UTC](https://boards.straightdope.com/t/what-makes-something-acidic-alkaline/262250/1 "2004-08-30T15:57:27Z")

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I know it’s something to do with hydrogen atoms, so could anyone explain to me exactly what makes something have a pH, how a neutraliasation happens? I would like explanations that go into the chemistry of it all but when I search about it, it gives me websites with complicated mathematical language and chemistry jargon.

Thanks.

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**Author:** ![CloudClever](https://avatars.discourse-cdn.com/v4/letter/c/9de0a6/32.png) [@CloudClever](https://boards.straightdope.com/u/CloudClever)\
**Post date:** [August 30, 2004, 4:56pm UTC](https://boards.straightdope.com/t/what-makes-something-acidic-alkaline/262250/2 "2004-08-30T16:56:03Z")

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IIRC, Acidic things have an over abundance of H+ ions, and Basic things have an overabundance of OH- ions (AFAIK process of elimination, Alkaline=basic).

Neutralization occurse when an H+ pairs up with an OH- ion (an ion being simply a charged particle), to produce H sub 2 O.

I think pH stands for power of H, or how much hydrogen ions there are in a log form, but I am not sure about that, so I won’t go into detail on pH, I vaguly remember doing something with it’s opposite, pOH

I really love chem, I’m taking a couple chem classes this year in University, to explore it as a career option. I had a great HS chem teacher.

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**Author:** ![Fuji\_Kitakyusho](https://avatars.discourse-cdn.com/v4/letter/f/f0a364/32.png) [@Fuji\_Kitakyusho](https://boards.straightdope.com/u/Fuji_Kitakyusho)\
**Post date:** [August 30, 2004, 5:45pm UTC](https://boards.straightdope.com/t/what-makes-something-acidic-alkaline/262250/3 "2004-08-30T17:45:12Z")

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Just about correct - in actual fact, free protons (H+ ions) can’t exist by themselves in aqueous solution - they combine with a water molecule to form a hydronium ion (H3O+).

pH stands for “potence hydronium”, or something like that, and is equivalent to the negative base-10 logarithm of the [H3O+] concentration.

For pure water, the tendency of water molecules to dissociate into [H3O+] and [OH-] ions is very low. This “K” value, as it is commonly known, is 1E-7 for water, giving a pH of 7. Low pH indicates an acidic solution, while high pH indicates a basic or alkaline solution.

Neutralization occurs when an H3O+ is reacted with an OH- to form a water molecule. The [H3O+] concentration decreases, hence the pH increases.

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**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\
**Post date:** [August 30, 2004, 6:04pm UTC](https://boards.straightdope.com/t/what-makes-something-acidic-alkaline/262250/4 "2004-08-30T18:04:59Z")

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IAACM (I am a chemistry major) but I’m used to thinking of pH in context of aqueous solutions. What is it that makes a soil acidic or alkaline? The presence or absence of various metals and other compounds?