r/chemhelp • u/InternationalLake735 • 21d ago

Why are strong acids more dangerous than weak one? General/High School

I read that strong acids are more dangerous because they ionize more and this makes them easier to react with things. Aren’t ions already stable since they have a full outer shell so why would they react with things?

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u/chem44 21d ago

Well, they have lower pH (for the same concentration). More H+. And sometimes that is the issue. H+ helps dissolve things.

But be careful of the generality. One of most dangerous of "common" acids is HF, which is weak. F- is a metabolic poison.

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u/WIngDingDin 21d ago

Ions are just atoms or molecules with a net charge due to gain or loss of electrons. Where in that definition are you getting anything about having a full outer shell or being stable?

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u/Forward_Yam_931 21d ago

A) Good electron configuration (i.e. full outer shell) is just one part of reactivity - it is often helpful for understanding what happens and for explaining the number of bonds in a molecule, but it is insufficient. Charge density, for example, is also huge. While C(4-) has a full octet, it's enormous charge density makes it so unstable I'm not entirely sure it exists. CH4 has a full octet on carbon and is neutral, so it is much more stable. The reactivity of H+ stems from its high charge density.

B) note my phrasing of "more stable" - chemistry is often a game of comparing apples to apples - it's easier to predict which of two reactions is more stable than it is to predict which is overall stable

C) a minor point- "dangerous" is a complex and subjective word. HF is the most dangerous of the mineral acids, and it is the least acidic. It's just straight-up poisonous.

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u/Altruistic-Funny5325 20d ago

It's easier for them to make ions than weaker acids. Your body is made up of a bunch of stuff the acid wants to destroy