Does mass change when you add alka seltzer to water??

It produces carbon dioxide when an Alka-Seltzer tablet dissolves in water. In the bath, the carbon dioxide dissolves and then emerges as a gas from the solution.

This carbon dioxide gas has mass, but it escapes from the container and diffuses into the atmosphere because it is a gas.

The mass loss from the container is directly calculated by the analytical balance.

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.