Final answer:
In the Brønsted-Lowry definition, an acid is a proton donor. HCN is the only substance listed that can act as a Brønsted-Lowry acid by donating a proton. Examples include reactions where HNO3, PH₂+, and H2S each donate a proton to form water and their respective conjugate bases.
Step-by-step explanation:
The question asks which of the given substances would most likely act as a Brønsted-Lowry acid. According to the Brønsted-Lowry definition, an acid is a substance that can donate a proton (H+). Out of the substances listed, HCN (hydrogen cyanide) is likely to act as an acid because it can donate a proton, forming CN- as its conjugate base.
Substances such as CCl₄ (carbon tetrachloride) and Mg(OH)₂ (magnesium hydroxide) do not typically act as acids in Brønsted-Lowry terms. CCl₄ does not have a hydrogen to donate, and Mg(OH)₂ is actually a strong base, as indicated in certain reference tables.
Here are examples of suitable net ionic equations for species acting as Brønsted-Lowry acids:
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- HNO3 (nitric acid) + OH- → NO3- + H2O
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- PH₂+ (phosphonium ion) + OH- → PH2 + H2O
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- H2S (hydrogen sulfide) + OH- → HS- + H2O