states of matter- bag bomb! LIQUID - Pour 1/4 cup of warm water into a ziploc bag. Next, add 1/2 cup of vinegar to the water (food coloring optional). SOLID - In a tissue, dump 3 tsp. of baking soda. Fold the tissue up like a square.Zip it up, let go of the pouch, and watch the bag expand - GAS! Soon the bag will look like a giant bubble. Hold it up and look what's happening inside, an acid-base reaction, creating CO2!