Chemical changes - Contenido educativo
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Explantion and examples of chemical changes.
Hi guys, today we're going to explain the chemical changes and the chemical reactions.
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You know quite a lot about chemical changes now.
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And I want you to have a look at this screen.
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In the screen, apart from me, I'm going to stay here,
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you will have this mind map here, which is the explanation of the whole unit.
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So, we will explain it little by little.
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This is everything you need to know from this explanation.
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And here on the right, you can see the vocabulary that you need to know to understand this lesson.
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So, to start with, let's go with the vocabulary first.
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And let's see.
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The first word is non-reversible.
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No reversible
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What does it mean?
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Look at this symbol
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Este es el símbolo de deshacer de los ordenadores
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So, something non-reversible
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It means que no puede ser deshecho
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No es reversible
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Second word
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Absorbed
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Absorber
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Release
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Expulsar
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Combustion
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which is the same as burning
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and means both of them combustion
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combustion o quemado
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and finally fuel
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combustible
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sometimes it's used also as gasolina
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so if you look at the words
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you've got also some drawings
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that may help you to understand the meaning.
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And pay attention to the pronunciation too, please.
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So once we know this, we can continue with the explanation.
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First of all, chemical changes.
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Chemical changes are non-reversible.
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They cannot be undone.
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No pueden ser desechos.
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So, for example, if I got these popcorns, if I have the corns, los granitos de maíz, I put them in the microwave when they are inside the package.
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And with the heat of the microwave, they change and we get these popcorns.
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You cannot have the corns as they were before because it happened a chemical reaction.
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So, this means that the atoms in the substances rearrange, se reorganizan, to form new substances.
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Suceden una serie de cambios en las sustancias que crean una nueva sustancia
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y lo que ha sucedido es que sus átomos se han reordenado, reorganizado.
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so all this process we are talking about
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the process is called chemical reaction
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the process of combining two substances
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to get a new one
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a new substance with different properties
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ok
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so this is the main part of the lesson
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the chemical reactions
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but you need to know
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there are two types of chemical reaction.
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The first one is endothermic
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and the second one is exothermic.
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Endothermic refers to the inside.
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It refers to absorb heat.
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O sea que una reacción química endotérmica
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es aquella en la que se absorbe calor.
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A good example of this
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is the photosynthesis that happens with the plants.
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The plants, they get, they absorb the heat
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to produce a chemical reaction to get the food.
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This is endothermic chemical reaction.
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And on the other side, we have exothermic.
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Es aquella en la que se expulsa calor.
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The exothermic release heat.
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Si se expulsa calor, this means that thermal energy is produced.
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Thermal energy, energia calorífica.
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For example, digestion is an example of exothermic chemical reaction.
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The temperature of our body increases during digestion.
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or explosion or
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the most representative of this exothermic
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chemical reaction is
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combustion. Conversion is an exothermic.
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In combustion, you can see
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the examples at page 12, you need
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always oxygen plus
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a fuel, fuel was combustible, o sea que si combinamos un combustible y oxígeno, we get
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thermal energy, que es lo mismo que calor, ok?
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So, you can look up the ways of getting hot or thermal energy, there are three good examples
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in the book, so if you want you can stop the video, have a look at the examples and then
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you continue watching the video but remember that oxygen is always necessary that's why
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i recommend you to do the experiment that you have at page 13 the exercise for and see what happens
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for example i want to show you here i'm gonna do now combustion with the candle i need
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a fuel and I need also
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oxygen and with this I produce
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thermal energy
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but sometimes when we produce
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thermal energy we are happy
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because normally we burn things or we
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do combustion to produce thermal energy to cook
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to heat our houses or i don't know to to be able to move our cars or the buses the transports
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but with that combustion we produce other substances and these substances are not so good
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Why? Because they produce, in the combustion, we can produce carbon dioxide particles,
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a sulfur dioxide that can damage the environment.
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So let's see here an example.
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Let's keep this here so you can see this better.
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One effect that these substances can cause is the global warming, el calentamiento global.
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Carbon dioxide in the atmosphere can cause global warming.
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Another one is that these particles, which is the pollution, la contaminación, can cause respiratory illnesses to the human beings.
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and the third one sulfur dioxide can be mixed with the rainwater and produce the acid rain
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that damages also the environment so i have led to you in the
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in google classroom and in the website i'm gonna let you a document with some videos about global
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warming and acid rain they are very interesting they are from national geographic they have
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subtitles and they are a very good explanation of these bad consequences of combustion
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so this is all for today guys i hope you understood if not we will see each other i hope
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thursday and we can you can ask me questions in the video llamada okay see you soon
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- Autor/es:
- Lorena García Blanco
- Subido por:
- Lorena G.
- Licencia:
- Reconocimiento - No comercial - Compartir igual
- Visualizaciones:
- 9
- Fecha:
- 8 de abril de 2024 - 20:17
- Visibilidad:
- Clave
- Centro:
- CP INF-PRI LUIS BELLO
- Duración:
- 09′ 24″
- Relación de aspecto:
- 4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
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