Mint chocolate leaves – changes of state

Valentines day is coming up, so I thought we’d do some activities based around that, starting with some chocolate leaves.

What you need

Mint leaves

Chocolate ( we used a lovely 70% dark kind )

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Instructions

Melt the chocolate, I did ours quickly in the microwave, but if you wanted to show the children the chocolate actually melting you could place it in a bowl inside another bowl containing very hot water.

Check the chocolate isn’t too hot, and then dip the leaves into it.

Place in the fridge to cool.

Gently peel the leaf away from the chocolate. What do you think? They’d be yummy on some ice cream I think!

Can you see the imprint of the leaf veins in the chocolate? Veins form part of the transport system of a plant. They carry water and nutrients to to the leaf and remove the sap from the leaf. They also help give the leaf its structure.

This experiment is a great way to demonstrate the process of changing state from Solid to liquid and back again.

Everything we know exists in three states: A solid, A liquid or a Gas!

Substances  can change from one state to another by different processes.

SOLID  ––> LIQUID = MELTING

LIQUID ––> GAS = EVAPORATING/BOILING

GAS  ––> LIQUID = CONDENSING

LIQUID ––> SOLID = COOLING/FREEZING

When the chocolate was heated it changes from solid to liquid and that was an example of melting and when we move back from a liquid into a solid it is an example of cooling/freezing.

The reason this happens is because when you provide heat the particles that make up the solid are given energy which cause them to vibrate and then break the bonds holding them together. As they cool they lose this energy and so forms bonds again but not in the same shape…this is why we can mould chocolate and other substances!