Science Demonstration 1
Science
Science Class Demonstration
So we've discussed physical and chemical changes, can anybody tell me the difference between physical and chemical changes? What you got? Chemical change is something that you can't go back. You can't separate. And a physical change is in the local I guess. But you can like change it back to normal state. Okay, cool. Yeah, so my physical changes are just a change in appearance, right? Chemical changes result in a new substance, right? And so it's kind of hard to change that back to its original state. Sometimes we can do it, but it would take a decent amount of work to get that done, right? So you have seen candles burning before, right? Is this a chemical or a physical change? Chemical. How do you know it's a chemical? Because the candle can not be reversed. Okay. Can't be reversed. So if this is a chemical change, what do you think my reactants are? But that's again in the carbon dioxin to the end.
Oxygen and carbon dioxide in the air, okay? What's burning? What the wick? So if the width is burning, why does it take so long to get through? Very good. So in this situation, really, yes, the wick is burning, but what's reacting here is my wax and like you said, oxygen from the air. All right, those are my reactants. So we've talked about reactants being on one side of our chemical equation, right? So what about our products? What do you think a product of this reaction is? What's it changing into? And over the outside. Melted wax and carbon dioxide. Okay. Any other guesses? Well, that surprised you if I said one of them is water. So water is often a product of burning. So when we burn things and this actually happens in your body too. When you burn calories and you burn the food that you take in you burn that energy a byproduct of that is water. So if I remove one of the reactants from this, can the reaction still occur? No, it can't. So if I were to remove the oxygen from this, it might take a little bit to burn up and use all of that auction.
The whole time this is burning them, I'm still using oxygen, right? But eventually, this is a big jar so it might take a little bit, but eventually I'm going to burn out all of the oxygen. And I can't make any more products, right? We're almost there. We're almost there. And there we go. So it took a while, but eventually all of the oxygen that was left in this jar burned up. So when we're working with our chemical reactions, when we are. Doing our chemical equations, we have to know that I have to have a certain amount of reactants to make my problems, right? And once those are reactants are used up, I'm not going to make any more products, right? Cool.