Hot Chocolate Science And STEM Activities | Explore Mixtures And Solutions With Kids

National Hot Chocolate Day is January 31st. What an excellent time to explore the science behind creating a good hot chocolate recipe. 

Creating a delicious cup of cocoa involves understanding the science of solubility. Solubility is how well a substance dissolves in water. Each ingredient in hot chocolate behaves differently in water. Students can observe the properties of the hot chocolate ingredients by placing them in water at different temperatures. Any age can do this. Teachers can expand the discussion with older students.

Instant hot chocolate powder is easy to make. All you need is water and the powder mixture. That powder contains the necessary ingredients to make the hot chocolate rich and creamy. Below is a description of the ingredients and how they behave in water.

Cocoa powder is unique because it is only soluble in warmer water; even then, it only forms a temporary mixture. The image below shows cocoa powder in cold water versus hot water. Students are always surprised by the results. Cocoa powder is hydrophobic, which means water-fearing. The fat in the cocoa powder needs to melt so it can mix with water.

On the left is cocoa powder in cold water.  On the right is cocoa powder in hot water.

Sugar is the ingredient that makes hot chocolate sweet. Powdered sugar dissolves smoother than the larger crystal sugar molecules, but you can use granulated or brown sugar, too. Sugar creates an actual solution. A solution is a mixture where one substance dissolves evenly in another. It will dissolve in water at any temperature completely. The powdered sugar disappears, but it is still there.

Powdered milk is a substitute for liquid milk. It is also called instant milk, dried milk, or milk powder. They evaporate the water from the milk and leave behind the dry ingredients. Powdered milk easily mixes with the water because the particles are tiny. The mixture will be white. Powdered milk helps stop the hot chocolate from being clumpy. It gives the hot chocolate its rich flavor.

Cornstarch is the ingredient that might surprise you. Cornstarch is a substitute for soy lecithin found in store-bought powders. Cornstarch is an emulsifier. An emulsifier helps disperse the fat in the cocoa powder and powdered milk, making them more water-soluble. It helps keep the cocoa powder from separating and gives the hot chocolate a creamy texture. It will mix in cold or hot water but may settle on the bottom because it is not a true mixture.

Help your students discover the science of hot chocolate with a science and STEM unit. Students will test the ingredients and take what they have learned to create a yummy hot chocolate recipe. Looking at hot chocolate from a science perspective makes it memorable, educational, and FUN! 

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