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Hello everyone! Okay, today we are going to talk about physical and chemical

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changes. Remember last day we were talking about the change of states from

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gas to liquid, from liquid to solid and the way back? Today is different. We have

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to distinguish between these two things and it's very simple. I am going to use

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these two pieces of paper. This is normal paper. If I just make a ball with it, this is still paper, same

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properties. Okay? So this means that is a physical change. Just change the physical

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same aspect, but the properties are the same. If I just break here, many pieces. There's

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too many neurons. This is still paper, same properties. This is a physical change. But

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So what happens if I take one of these pieces and a lighter, don't do this at home, remember,

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just with your parents, and you burn it.

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You can see how it burns, the smoke, and the dust.

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Can you see here?

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This is not a physical change, this is a chemical.

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That means that the dust is not paper anymore, the properties are different.

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So when we burn it, this part of it becomes another thing, okay?

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Dust with other properties different from the paper.

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One of the characteristics of the physical change is it cannot be undone.

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So the dust cannot be paper again, okay?

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Let's go with another example.

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Here I have a glass with a piece of ice, okay?

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If we go to the microwave, okay, we put the ice in just for some seconds, okay let's see,

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25.

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Okay, what do you think?

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What do you think we are going to find here?

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Of course, as you know, we have water and vapor too, you can see it.

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okay now here is my question

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this change what do you think it's physical or chemical change

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being that as we said in the chemical the property changed and the physical they don't change

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and in the chemical they cannot be undone

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and with the physical we can do it in the other way. So that means that this is physical change.

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This is a physical change because the water, even if it's in another state, it's still water. The

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properties are the same. And if we put it in the fridge after maybe an hour, hour and a half,

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or two hours we will get ice again okay this is the main difference I hope you

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have understood this you have two more videos please watch them please and if

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you have any questions just send me an email okay bye bye