Which of the following would most likely act as a Bronsted-Lowry acid?

A. [tex]\(OH^{-}\)[/tex]
B. [tex]\(HCN\)[/tex]
C. [tex]\(CCl_4\)[/tex]
D. [tex]\(Mg(OH)^{+}\)[/tex]



Answer :

To identify which of the given compounds would most likely act as a Bronsted-Lowry acid, it’s essential to understand the definition of a Bronsted-Lowry acid. According to Bronsted-Lowry theory, an acid is a substance that can donate a proton ([tex]\(H^+\)[/tex]).

Let’s analyze each of the given compounds:

1. [tex]\(OH^{-}\)[/tex] (Hydroxide ion):
- The hydroxide ion typically behaves as a base because it tends to accept a proton ([tex]\(H^+\)[/tex]) to form water ([tex]\(H_2O\)[/tex]). Therefore, [tex]\(OH^-\)[/tex] is not likely to act as an acid.

2. [tex]\(HCN\)[/tex] (Hydrogen cyanide):
- One of the hydrogens in this molecule can be donated as a proton ([tex]\(H^+\)[/tex]), converting the molecule into the cyanide ion ([tex]\(CN^-\)[/tex]). Thus, [tex]\(HCN\)[/tex] has the ability to donate a proton, making it a Bronsted-Lowry acid.

3. [tex]\(CCl_4\)[/tex] (Carbon tetrachloride):
- [tex]\(CCl_4\)[/tex] is a covalent molecule with no easily donated protons. It does not have any hydrogen atoms from which a proton can be donated, so it cannot act as a Bronsted-Lowry acid.

4. [tex]\(Mg(OH)^+\)[/tex] (Magnesium hydroxide ion):
- This compound is more complex because it can potentially act as either a weak acid or a weak base. However, it contains a hydroxide ion ([tex]\(OH^-\)[/tex]), which increases its likelihood of behaving as a base by accepting a proton, rather than donating one.

Given these observations, [tex]\(HCN\)[/tex] (hydrogen cyanide) is the compound most likely to act as a Bronsted-Lowry acid because it can donate a proton.

Thus, the answer is:

[tex]\[ \boxed{HCN} \][/tex]
(Option 2)