If you’re ever in a pinch and you have no cold packs available or ice, and you have the ingredients on hand, you can totally make your own instant cold pack at home.
This can be a fun little experiment to do with kids to explain endothermic reactions.
You will need the following:
- A plastic bag
- 1 tablespoon of citric acid
- 1 tablespoon of baking soda
In your plastic bag mix the citric acid and baking soda together.
When you’re ready for the cold pack, simply pour some water into the bag and allow the reaction to take place.
It's important that you do no seal your plastic bag at this stage as the reaction will create a lot of gas and cause your bag to explode.
The reaction of the water and chemicals will instantly cool the bag down. It won't get as cold as ice but it will get cold to touch.
For fun measure the temperature of the water before the reaction and then after the reaction to see how much colder it has gotten.
You can also do this experiment in a glass container, you don't have to use a plastic bag.
If you want the instant ice pack to last longer then use larger quantities of citric acid, baking soda and water.
Viola! You have your own instant cold pack, while it may not get as cold as the store-bought ones it will certainly be cold to touch.
You can watch a video of this experiment below: