* Alka-Seltzer's Reaction: Alka-Seltzer contains sodium bicarbonate (baking soda) and citric acid. When it comes in contact with a liquid, these ingredients react to produce carbon dioxide gas, causing the fizzing.

* Vinegar's Acidity: Vinegar is a dilute solution of acetic acid. The higher acidity of vinegar compared to alcohol (even strong alcohol like vodka) will speed up the reaction between the sodium bicarbonate and citric acid in Alka-Seltzer, leading to faster dissolution.

* Alcohol's Impact: While alcohol can also dissolve some of the ingredients in Alka-Seltzer, its acidity is much lower than vinegar. It won't trigger the same rapid reaction and gas production.

In Summary: The faster dissolving of Alka-Seltzer in vinegar is due to the vinegar's higher acidity, which acts as a catalyst for the reaction between the ingredients in Alka-Seltzer.