How does water temperature affect the rate of gas
production in Alka-Seltzer?

In the hot water the tablet should have more vigorously produced bubbles than in the cold water. The higher the temperature, the faster the molecules move—and the more likely it is that the bicarbonate will contact hydrogen in just the right way for the chemical reaction to occur and produce carbon dioxide bubbles.

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.