# Hazardous Materials Classification

**URL:** <https://boards.straightdope.com/t/hazardous-materials-classification/847452>\
**Category:** Factual Questions\
**Created:** [February 3, 2020, 11:22pm UTC](https://boards.straightdope.com/t/hazardous-materials-classification/847452 "2020-02-03T23:22:05Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Ranger\_Jeff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranger_jeff/32/2065_2.png) [@Ranger\_Jeff](https://boards.straightdope.com/u/Ranger_Jeff)\
**Post date:** [February 3, 2020, 11:22pm UTC](https://boards.straightdope.com/t/hazardous-materials-classification/847452/1 "2020-02-03T23:22:05Z")

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I’m having difficulty finding the Hazardous Materials Classification chart for H2CO3. I mean the graphic with the 4 diamonds forming a larger diamond, like [this](https://www.stonehousesigns.com/sites/default/files/Hazardous_Material_Classifications_WX90_0.jpg).

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [February 3, 2020, 11:34pm UTC](https://boards.straightdope.com/t/hazardous-materials-classification/847452/2 "2020-02-03T23:34:46Z")

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[It’s 0-0-0-0](https://beta-static.fishersci.com/content/dam/fishersci/en_US/documents/programs/education/regulatory-documents/sds/chemicals/chemicals-c/S25234.pdf), about as perfectly safe as you can get. Even California doesn’t consider it hazardous.

For what it’s worth, I Googled “Materials safety data sheet H2CO3”.

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**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\
**Post date:** [February 4, 2020, 1:05am UTC](https://boards.straightdope.com/t/hazardous-materials-classification/847452/3 "2020-02-04T01:05:02Z")

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Chronos has posted the MSDS for \<1% Carbonic Acid. It’s important to know the pressure and concentration to give you a good answer.

CO2 is also known as Carbonic acid gas and Carbonic anhydride - see here [ICSC 0021 - CARBON DIOXIDE](https://www.ilo.org/dyn/icsc/showcard.display?p_lang=en&p_card_id=0021&p_version=2)

Also here is the NFPA 704 sign for CO2 - [NFPA 704 Sign for CO2 | CO2Meter.com](https://www.co2meter.com/blogs/news/nfpa-704-sign-for-co2)

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**Author:** ![Cleophus](https://avatars.discourse-cdn.com/v4/letter/c/a88e57/32.png) [@Cleophus](https://boards.straightdope.com/u/Cleophus)\
**Post date:** [February 4, 2020, 2:22pm UTC](https://boards.straightdope.com/t/hazardous-materials-classification/847452/4 "2020-02-04T14:22:38Z")

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> [@Ranger\_Jeff](#):
>
> I’m having difficulty finding the Hazardous Materials Classification chart for H2CO3. I mean the graphic with the 4 diamonds forming a larger diamond, like [this](https://www.stonehousesigns.com/sites/default/files/Hazardous_Material_Classifications_WX90_0.jpg).

The chemical formula you posted is for carbonic acid, which is a very weak acid that forms in small amounts when CO2 is dissolved in water and is practically harmless. I’m having trouble thinking of a reason you would need to post a hazardous material classification for it. Is there some larger task at hand?

ETA: Are you maybe thinking of carbolic acid (phenol)?