# Is the pH of antimatter the reverse of the pH for matter?

If it does have a pH, I mean. Though I don't see why it shouldn't have it.

Both the Brønsted-Lowry and Lewis definitions of acid have to do with the ability of a substance to accept, or provide protons or pairs of electrons in certain reactions.

I got interested into this when I learned that the electric charges for antimatter particles are the opposite of those for matter particles (i.e.: positively charged positrons orbiting around negatively charged antiprotons).

So I was thinking... If I mixed anti-hydrogen chloride with anti-sodium hydroxide to make anti-salt, it would be the anti-HCl that would be donating negative charged ions, and the anti-NaOH that would be providing the positive charges.

Does that mean that the pH of a matter substance and its antimatter counterpart are reversed in relation to each other? Would anti-LSD be a base instead of an acid?

Edit: I understand that getting matter in contact with antimatter will cause anihilation. I know that trying to neutralize an antimatter acid with a matter base would be great fun would never work. While asking this question I had a "bizarro" anti-matter world in mind. I was thinking, for example, how some anti-lemmon battery would work, since the anti-ions would be going in different ways when compared to a lemon battery in our matter world.

• My gut instinct is that, since acid and base are relative terms, antimatter acids would still be acids relative to antimatter bases. Relative to matter bases? They wouldn't even interact chemically (they would annihilate quantum mechanically pretty quickly), so it is a non-question. – jwimberley Jul 11 '14 at 14:14
• @jwimberley I understand that. But due to the charges involved, an acid may react in different ways depending on the environment. I imagine that in a bizarro anti-world, an anti-lemon battery would behave somewhat different from what it does in our world due to (anti)anions and (anti)cathions going the other way around. – Renan Jul 11 '14 at 14:19
• Anti-atoms and -molecules should behave in exactly the same way as 'normal' ones. The overall minus-sign does not affect any of their properties as long as the are in no contact with 'normal' matter. – Aecturus Jul 11 '14 at 14:21
• @AlphaCentauri okay, I just thought of how my anti-lemmon battery example is bad. Ultimately everything charge-related would be so reversed that I don't think there would be any noticeable difference. – Renan Jul 11 '14 at 14:25
• You better rename the property $p\bar{p}$ :-) .(that's supposed to be the symbol for an antiproton, dunno if there's an official symbol for antiHydrogen) – Carl Witthoft Jul 11 '14 at 15:52

## 1 Answer

The reaction of acids and bases to form water and salts is governed by electromagnetism: the transfer of charge carriers from one nucleus to another. Electromagnetism is invariant under $CP$, the transformation that changes particles into antiparticles. So the reaction of anti-acids and anti-bases to form anti-water and anti-salts would, to an excellent approximation, proceed exactly as in the matter case.

Even if it were possible to produce an aqueous solution of anti-acid, I don't think it'd be useful to define its pH — if you were to react your anti-solution with a matter solution with well-defined pH, you'd make a boatload of fast pions and wouldn't do any chemistry at all. Carl Witthoft cleverly suggests in a comment to talk about the p$\mathrm{\bar H}$ of an anti-chemical.