Question 28
A cold pack is made by putting 10 cm³ sodium hydrogen carbonate (baking soda) in a sealable plastic bag and adding 30 cm³ dilute ethanoic acid (vinegar). Make a tiny pinhole near the top of the bag before mixing. Seal the bag and shake it gently to mix the reactants. Wear safety goggles and gloves, work in a well-ventilated area and handle chemicals with a spoon or spatula. Keep the vent hole above the liquid and unblocked; carry out this school investigation under teacher supervision. Predict what you would observe if you put the bag in a dish of warm water. Give a reason for your answer.
