Question

in each row, select the molecule with the highlighted h atom that is more acidic.

Explanation:

Row 1:

Step1: Analyze the groups

The first molecule has a protonated hydroxyl group ($\ce{-O^+H_2}$) and the second has a neutral hydroxyl group ($\ce{-OH}$). A protonated oxygen (in $\ce{-O^+H_2}$) is more electron - withdrawing, making its $\ce{H}$ more acidic.

Step2: Choose the more acidic

So the first molecule (with $\ce{O^+ - H}$) has a more acidic highlighted $\ce{H}$.

Row 2:

Step1: Compare $\ce{O - H}$ and $\ce{S - H}$

Sulfur is larger than oxygen, so the $\ce{S - H}$ bond is longer and weaker. A weaker bond means the $\ce{H}$ is more easily dissociated (more acidic). The first molecule has $\ce{O - H}$, the second has $\ce{S - H}$.

Step2: Choose the more acidic

So the second molecule (with $\ce{S - H}$) has a more acidic highlighted $\ce{H}$.

Row 3:

Step1: Compare $\ce{S - H}$ and $\ce{O - H}$

As sulfur is larger than oxygen, the $\ce{S - H}$ bond is weaker than the $\ce{O - H}$ bond. A weaker bond implies a more acidic $\ce{H}$. The first molecule has $\ce{S - H}$, the second has $\ce{O - H}$.

Step2: Choose the more acidic

So the first molecule (with $\ce{S - H}$) has a more acidic highlighted $\ce{H}$.

Row 4:

Answer:

s:
Row 1: The first molecule (with $\ce{O^+ - H}$)
Row 2: The second molecule (with $\ce{S - H}$)
Row 3: The first molecule (with $\ce{S - H}$)
Row 4: The second molecule (with $\ce{S - H}$)