To determine which of the given compounds would most likely act as a Bronsted-Lowry acid, we need to consider the Bronsted-Lowry definition of an acid. According to the Bronsted-Lowry theory, an acid is a substance that can donate a proton (H+ ion).
Let's analyze each compound provided:
1. OH⁻ (Hydroxide ion):
- The hydroxide ion (OH⁻) has a negative charge and is known to accept a proton to form water (H₂O). Thus, OH⁻ is a base, not an acid because it accepts a proton rather than donating one.
2. HCN (Hydrocyanic acid):
- HCN contains hydrogen that it can donate, forming the cyanide ion (CN⁻) in the process. Thus, HCN can act as a Bronsted-Lowry acid because it can donate a proton (H+).
3. CCl₄ (Carbon tetrachloride):
- CCl₄ is a molecule of carbon tetrachloride and it does not have any hydrogen atoms to donate as protons. Therefore, it cannot act as a Bronsted-Lowry acid.
4. Mg(OH)⁺ (Complex ion):
- The complex ion Mg(OH)⁺ typically acts as a base because it can accept an additional proton to form Mg(OH)₂. Therefore, Mg(OH)⁺ does not donate a proton; rather, it can accept one.
After analyzing all the options, we conclude that:
- HCN is the compound that is most likely to act as a Bronsted-Lowry acid, since it has the ability to donate a proton (H+).
Therefore, the correct answer is HCN.
