The equivalent weight \( E \) of an acid is linked to its molecular weight \( M \) using this formula:
\[
E = \frac{M}{n}
\]
Where:
- \( n = 2 \) for a dibasic acid (because it donates two protons)
- \( E = 12 \)
Replacing values in the equation:
\[
12 = \frac{M}{2}
\]
Solving for \( M \):
\[
M = 12 \times 2 = 24
\]
Therefore, the molecular weight is 24.