What are chemical changes?

Hey there!

Before we see the page I recommend you to see this video

We have to understand the difference between physical and chemical changes.

A physical change means that the shape, form or state change but the substance is the same. The most typical example is with water when we turn liquid water into gas or into ice.

A chemical change is when the substance that we have at the begging it changes into a new one. For example, when we burn paper, at the begging we have a piece of paper and in the end we have ashes, dioxide carbon and water vapor.

Let's go now with the page that we have for today

Here you have the audios
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When we have a chemical change it can produce or absorb energy.

When the reaction produces energy we call it exothermic (exo- means outside, thermic means heat), like when we have combustion.

When the reaction absorbs energy we call it endothermic (endo- means inside), one example of this is the photosynthesis.

The combustion is oxidation, but really fast. On Monday we will see more about oxidation.

Homework: Exercise 3

Audio