What are the products when Alka Seltzer dissolves in water? Is it water and carbon dioxide, i'm not really sure with that
Carbon dioxide, water, and sodium citrate solution
Alka Seltzer is a mixture of sodium bicarbonate, citric acid, and acetyl salicylic acid. The sodium bicarbonate and citric acid are there mainly to create a pleasant tasting fizzy antacid solution. The acetyl salicylic acid is "aspirin", the active ingredient which is a pain killer, and this will only be present in small quantity probably around 250 mg per tablet.
When water is added, the sodium bicarbonate and citric acid are dissolved, forming aqueous ions which react to yield carbon dioxide, water, and the sodium salt of citric acid (sodium citrate). The pH of the final solution is sufficiently basic to act as a remedy for acid stomach and the aspirin simply dissolves in the water, so it can be consumed more easily so that it can fight headaches or similar types of pain.
The reaction is:
Citric acid (aq) + Sodium bicarbonate (aq) -> Carbon dioxide + water + Sodium citrate