# Do acids and bases neautralize over time? **URL:** \ **Category:** Factual Questions\ **Created:** [September 3, 2008, 6:00pm UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896 "2008-09-03T18:00:24Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [September 5, 2008, 4:11am UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896/21 "2008-09-05T04:11:23Z")
> [@WarmNPrickly](#): > > The solid will also pick up CO2. But this only happens if it is exposed to air. In a sealed container, you wont have much of a problem You wouldn’t want to do precision analytical work with it though. Fresh, reagent grade NaOH pellets typically contain about 1% sodium carbonate by weight. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [September 5, 2008, 12:44pm UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896/22 "2008-09-05T12:44:32Z")
> [@Interconnected\_Series\_of\_Tubes](#): > > Technically the solid picks up _water_ from the air, which picks up CO2. Or am I mistaken? The solid doesn’t have a pH at all. No, there’s no reason why solid NaOH can’t react directly with gaseous CO[sub]2[/sub], which is why you’d want to keep a container of solid sodium hydroxide sealed. It would be a fairly slow reaction, though. The fact that solid NaOH does not have a pH is irrelevant. ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [September 5, 2008, 1:25pm UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896/23 "2008-09-05T13:25:22Z")
> [@WarmNPrickly](#): > > That’s an interesting question that I have never considered. According to [wikipedia](http://en.wikipedia.org/wiki/Self-ionization_of_water) pKw is actually 13.9965 at room temperature (They use the CRC as a cite). I think that would make a neutral pH slightly lower than 7.0. Well, if you’re paying attention to significant figures, half of 13.9965 is not lower than 7.0, actually. Nor is it lower than 7.00 (though it is lower than 7.000). ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [September 5, 2008, 1:49pm UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896/24 "2008-09-05T13:49:08Z")
I haven’t paid attention to sig figs since I was in high school. When I wrote papers for publication, I just calculated the error and chopped off the number at the right spot. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [September 5, 2008, 2:14pm UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896/25 "2008-09-05T14:14:19Z")
> [@GaryM](#): > > Watching an episode of How it’s Made the other day they mentioned that after aluminum cans were drawn to their final shape they were rinsed with deionized water “which has no Ph”. Now I’m not a chemist, but how can some liquid have no Ph? I’m no chemist either, but the pH of deionized water exists (and should be 7) but it is not easy to measure. There are very few ions in the water for a pH meter to use to get a reading. If you get the chance, put a pH meter into deionized water and you’ll see what I mean - it will give you numbers all over the place - 5, 8, 10, 6, and even if it does settle down at a particular value, that value will almost certainly not be 7. This has to do with how pH is **measured** , not with any **actual reflection of the concentration of ions** in deionized water. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [September 5, 2008, 2:27pm UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896/26 "2008-09-05T14:27:50Z")
To simplify, would it be accurate to say that if the storage medium is inert the acid/alkali will remain stable? ---
**Author:** ![Interconnected\_Series\_of\_Tubes](https://avatars.discourse-cdn.com/v4/letter/i/13edae/32.png) [@Interconnected\_Series\_of\_Tubes](https://boards.straightdope.com/u/Interconnected_Series_of_Tubes)\ **Post date:** [September 5, 2008, 3:56pm UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896/27 "2008-09-05T15:56:44Z")
> [@Really\_Not\_All\_That\_Bright](#): > > To simplify, would it be accurate to say that if the storage medium is inert the acid/alkali will remain stable? Assuming it’s not reacting with anything present in the airspace of the container - yes. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [September 5, 2008, 4:02pm UTC](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896/28 "2008-09-05T16:02:31Z")
> [@Really\_Not\_All\_That\_Bright](#): > > To simplify, would it be accurate to say that if the storage medium is inert the acid/alkali will remain stable? Depends on the acid/base. Acids such as nitric, sulfuric, hydrochloric, perchloric, phosphoric, and acetic are pretty stable as are inorganic bases and triethanolamine and ammonia. Alpha hydroxy acids, keto acids, deoxyribonucleic acids, and many organic bases will react or break down over time. Usually, you can slow the process by keeping such things in the refrigerator. [Previous page](https://boards.straightdope.com/t/do-acids-and-bases-neautralize-over-time/461896.md?page=1)