Question

Mrs. Smith is demonstrating a chemical change for her class. She places 15 grams of baking soda into a beaker. Next she adds 15 grams of vinegar to the same beaker. When the two compounds make contact, they bubble and fizz a great deal. She places the beaker on the balance and notes that the mass of the solution in the beaker is less than the expected 30 grams. Why is the mass of the solution in the beaker less than 30 grams?

Answer 1

The reaction in between baking soda (sodium bicarbonate) and vinegar (dilute acetic acid) generates carbon dioxide gas. This is because of the acid-base reaction. Vinegar is acetic acid dissolved in water and baking soda is a base called sodium bicarbonate. Initially, the reaction makes carbonic acid which is unstable. It quickly breaks down into CO₂ and water. This carbon dioxide, when released, causes the fizz and bubbles in the solution.

Since, the carbon dioxide released escapes into the air, the mass of the reaction solution decreases. So, there is a decrease in the mass of the beaker after the reaction.