What makes Alka Seltzer tablets fizz?

Alka Seltzer tablets contain solid sodium bicarbonate and citric acid. When dropped into water, sodium citrate, carbon dioxide, and water are formed:

The sodium citrate is a weak base. It neutralizes stomach acid (mainly HCl) by the following reaction:

Na3C3H5O7 (aq) + 3 HCl(aq) doublearrow H3C3H5O7 (aq) + 3 NaCl(aq)

Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! What makes Alka Seltzer tablets fizz?

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