DIY Cold Pack

Create An Endothermic Reaction! A what?! you ask... read on!

Hello there, Team Genius!

We’ve been thinking about Chemistry lately at Genius Box and wanted to share what we’ve learned with you!

Chemistry is a science that aims to explore and define the chemical properties of different substances. A substance can be thought of as any particular kind of object with constant properties. Consider a glass of water – the water inside of the glass is one type of substance. The glass itself is another type of substance.

The chemical properties of substances are characteristics that define the substances. For instance, some properties of water are that it is naturally clear, it freezes into ice at 32 degrees, and it does not burn. Typically, chemists (people who study chemistry) are interested in reactions between different chemicals. A reaction is the act of one chemical changing into another.

Imagine yourself at a bonfire. You build up a pile of wood and light it. It burns up for a while, then eventually goes out and leaves a pile of gray ashes behind. What you’ve just witnessed is a chemical reaction. All chemical reactions start with at least one substance, called the reactant (the wood that you lit at the bonfire), exchange energy in some form, typically either heat, cold, light, or sound (the light and heat from the bonfire), and end up with a final, new substance, called the product (the ashes that still remain in your bonfire pit).

There are many different types of chemical reactions. Some happen very fast (like the explosion of a firework on the Fourth of July), and some happen very slow (like the rust that builds up over years on an old car left out in the rain). Chemical reactions happen all around us, and in fact are happening inside you as you read this. Your body is taking whatever food you ate earlier, and through chemical reactions, adding to your muscles and bones as you grow and giving you the energy you need to walk around and even read this sentence.

What You Need:

· Resealable plastic bag

· Sponge

· Baking soda

· 2 limes

· Tablespoon

· Container for lime juice such as a measuring cup

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The Procedure // How-To:

1. Start by placing your sponge inside of your resealable bag. This will be the basis of your cold pack.

2. Add one heaping spoonful of baking soda into cold pack.

3. Squeeze the lime juice into a container, such as a measuring cup.

4. Add 2 tablespoons of the lime juice to your cold pack.

5. You should see the reaction happening between the baking soda and lime juice. Wait for the bubbles to go down, then seal your bag.

6. Squeeze the sponge inside of the bag so that the liquid inside is sucked into the sponge.

7. Feel the sponge; note whether there seems to be any temperature change. Voila!

What happened??!?

As we said earlier, every chemical reaction has three parts; reactants, energy transferred, and product.

Reactants- The reactants in this reaction were the two substances you started with, baking soda and lime juice.

Energy Transferred- The energy transfer in this reaction was the temperature change that took place. Your “cold pack” should have gotten a bit colder after the reaction took place. Real cold packs use much stronger chemicals, so the cooling effect is much more intense and noticeable.

Product- The product of this reaction was actually inside of the bubbles that formed after the reaction took place. Inside of these bubbles was a gas called carbon dioxide that formed when the baking soda and citric acid reacted. The products here literally changed into carbon dioxide, a completely new substance with completely different chemical properties.

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Yours in curiosity,

Kate & Shivangi

Resident Mad Scientists & Co-Founders, Genius Box