If I understand correctly, an acid corrodes things because the hydronium ion attracts electrons away from whatever it is reacting with. Do bases corrode things in a similar manner? with the metal cation operating in the same way as the hydronium ion (taking electrons)?
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$\begingroup$ Note that NaCl is corrosive too. $\endgroup$– PoutnikCommented Mar 14 at 7:06
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$\begingroup$ "Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. [....] In the most common use of the word, this means electrochemical oxidation of metal in reaction with an oxidant such as oxygen, hydrogen or hydroxide." from en.wikipedia.org/wiki/Corrosion Not exactly a perfect definition but useful. Starting from definitions is often helpful. $\endgroup$– Buck Thorn ♦Commented Mar 14 at 8:00
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$\begingroup$ Check difference between acidic corrosion and alkaline corrosion: tft-pneumatic.com/blog/… $\endgroup$– Nilay GhoshCommented Mar 15 at 17:17
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1 Answer
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It depends on what is being corroded.
Alkalis are caustic, because they saponify fats in skin, changing a fatty acid to soap.
Some bases are strong electrolytes, speeding galvanic corrosion.
Some metals react with the hydroxyl ion, such as zinc, forming the zincate ion, $\ce{[Zn(OH)4]^2-}$. The reaction of bases with aluminum is used to make hydrogen on demand, and to clean drains, as in this product.
Silica, $\ce{SiO2}$, is acidic, and reacts with bases to form silicates. For that reason, $\ce{NaOH}$ should not be stored in glass containers, which are attacked by dissolved $\ce{NaOH}$ (from moisture in air).
answered Mar 14 at 1:10
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2$\begingroup$ Hydroxide ion not hydroxyl radical. the oxidizer is water. The initial oxidation reaction is probably a one electron transfer to make H , Zn+ and OH- eventually OH- complexes with the Zinc ions to lower their potential and force the reaction. A radical mechanism while feasible on paper seems more complicated since OH-and H2O abound and OH radicals scarce. $\endgroup$– jimchmstCommented Mar 14 at 3:00
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$\begingroup$ @jimchmst, I stand corrected for my radical misstatement, admittedly at the root of the issue. They wouldn't be unionized (too Marxist for 'em). $\endgroup$ Commented Mar 14 at 17:17
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$\begingroup$ @DrMoishePippik To clean drains full of aluminum? Or with hydrogen? So confusing. $\endgroup$ Commented Mar 31 at 21:46
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1$\begingroup$ @PaulKolk, NaOH+ Al is mixed in a common drain cleaner, creating effervescent hydrogen and even more heat than created by NaOH dissolving. Reference will be added above. $\endgroup$ Commented Mar 31 at 22:37