The teacher puts vinegar into a small container of baking soda. the the combined substance begins to fizz and bubble. what type of change is this and why?

Astudent carefully transfers 30 g of water and 30 g of alcohol in a glass tube, forming two layers and filling the tube completely. after sealing the tube, the student mixes the solutions, and notices a bubble that forms in the tube. what is the mass of the contents in the glass tube after mixing?