Students in Mrs. Heather Carney's Grade 1 class made Mother's Day Bath Bomb gifts as part of STREAM. Each child took a turn either measuring, pouring or mixing the ingredients. The Baking soda (sodium bicarbonate), is a key ingredient in this bathtub explosion. When the high pH powder reacts with a low pH acid (Citric acid) it produces carbon dioxide bubbles. The Citric acid is the chemical, but it doesn't react with sodium bicarbonate until it gets wet. When they added water, that's when the reaction was apparent & exciting for the class to see!