Answer
The compound on the left is more acidic.
Work Step by Step
- The only difference between the structures is the triple bond.
- One of the carbons in the triple bond is $sp$ hybridized.
- A negative charge on an $sp$ atom is more stable than one in an $sp^2$ atom (from the double bond in the structure on the right).
- Therefore, the compound on the left is more acidic.
