Ammonium chloride absorbs thermal energy as it dissolves in water.

Rodrigo designed an airtight, watertight pouch. He put a carefully measured amount of ammonium chloride in it. He added a measured amount of water to the ammonium chloride, sealed the pouch tightly, and then wrapped the pouch around a small bottle of water.

Rodrigo's device is intended to bottled drinks. He can test how well his device works by measuring the total change in temperature of the Next, Rodrigo should see if he can use the results of his test to improve the of his design.