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Chemical Equations: How to Recognize and Classify Chemical Reactions

Added Jan 06, 2016 •

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everyone this is mr. Causey coming from beautiful Atascocita and my virtual studios and today we're going to talk about chemical reactions important understand chemical reactions in order to be able to write chemical equations and then move on to balancing some a big part of chemistry chemical reactions right so we've been doing all this stuff now to get into the real important things in this lesson we'll talk about chemical reactions signs of a reaction types of a reaction and reaction practice you need of course if you're going to table and apple Atomic ions list and hopefully you have mine if you don't you can go to mr. Causey. you should be able to get that download or just shoot me off an email you must know chemical names chemical formulas oxidation numbers the periodic table why you stand chemical bonding chemical reaction what is it chemical reaction is the rearrangement of the elements in the package to form new substances the reactants what are they that's the stuff you start with and there's an our products is make sure we not those are that's what you end up with your new substances and in that reaction there are the products  bonds are broken in the reactants to give us our new product so we see that the bonds are broken do hydroxide breaks down into sodium and hydroxide and hydrochloric acid breaks down into hydrogen and chlorine the elements are rearranged no remember the opposite attract so we have our new pairs and Walla bonds are formed and we get new products  that's just the basics of a chemical reaction you start off with some reactants their bonds break they rearranged and give us products here's an example nothing reacts with oxygen to produce carbon dioxide and water so first of all what are the reactants methane turn down our products carbon dioxide and water is our products  you're my signal booster cause you didn't balance it that's because that's not what I'm teaching in this unit what were engine is making sure we can write the reaction that we can recognize the reaction then we'll worry about balancing is Romero we're going to do a whole lesson on balancing in just a couple of lessons  show how do chemical reactions occur this much I can tell it's not by Magic All chemical reactions need energy that's right All chemical reactions need energy and this energy is called activation energy you see in order to get those bonds broken so that the ad can rearrange there's got to be some energy Einstein always said nothing changes unless something moves and I'll tell you nothing moves unless you have so you need an activation energy to get the process going and then we can have our chemical reaction no lot of reaction just start right off the bat and you don't have to worry about much they're called spontaneous reactions and they just start because they have a low activation take a lot of energy to start them they might get their energy from the room or the laboratory or wherever you doing the reaction or they make it the energy from the compounds are the elements themselves but they don't need a lot of energy to start they just start right off the bat and sometimes we have reactions that don't start spontaneous it's whatever established is a substance that speeds up the reactions by lowering the activation energy in a reaction If energy is released the products that are going to have less exothermic it's giving off energy more than just what the activation energy was the products are going to end up with less energy than the reactants exothermic reaction and then we have the other type of reaction to endothermic reaction this is where energy is absorbed and the products have more energy using information that you have about chemical bonds what you know about ionic bonds and covalent bonds and how they occur what you know about the octet rule and oxidation numbers all this information that you have gathered about elements and how they can come together to make compounds this knowledge can be used to help you predict how reactions might occur or we're going to use this information when we write chemical equations for our chemical reactions got to know the signs of a reaction because not everything that happens is it chemical reaction sometimes it's just a process like a dissolution process which is just dissolving so you need to pay attention to the signs of reaction and some signs are more conclusive than others  first signs of gas is produced when a gas is produced it's always a chemical reaction if there were no gases present and now you have gases watch a chemical reaction signs produced remember if I have two solutions and I put them together or Bushnell gas and I put them together and I get a precipitant that's a chemical reaction new substances definitely the production of heat or light that's not always completion that's a very good sign  color change that's a sign of a chemical reaction but it's usually accompanied by some Kawasaki gas produced a precipitate or light you can have a color change and not be a chemical reaction  an odor Gene that's like your famous put Mom's that's definitely a chemical reaction or just food spoiled when food spoils we smell it and that smell is coming from a chemical reaction think it through can you describe a chemical reaction do you know the difference between reactants and products do you know the signs that a chemical change occurred if you can say yes to all three of those then you're ready for the next section types of chemical reactions all right we need to learn to see what type so we can recognize them and categorize them  five basic types yes synthesis decomposition single replacement double replacement of course combustion we don't want to leave now let's go through down a look at it and see what what each one is synthesis two or more substances forming a new substance that's the general pattern of two things becoming one synthesis not as used to be called also a composition  but most synthesis now decomposition a substance decomposes into two or more substances can use your pattern single replacement one atom or ion replaces another in a substance so you notice I highlighted the one that is replaced she goes from the B to the A and usually in a single replacement you are going to get a pure substance something is going to be singled out  this case it was B life example double replacement the ions and two substances switch in an aqueous solution just like single replacement but we're going to switch on this usually occurs because one element is a little more reactive than another there's a pattern what is the switch Dora name combustion an exothermic reaction of a substance and oxygen and there's an example of it hydrogen and oxygen gives you H2 energy no that's a really cool experiment you can do you can separate out hydrogen and then ignited gives a great explosion I usually get a fireball from that but you need to do that safely talk to your chemistry teacher about possibly doing some experiment with hydrogen  here's an example of a hydrocarbon and some oxygen and that's the normal combustion most of us are used to  can I use combustion with nitrogen and here's an interesting thing though combustion is usually in an option it doesn't always have to involve logic there are some examples of situations where the general rule isn't true breaks the general and so you want to be aware that it could be a little different I know that there is also some combustion reactions that involve floor in fluorine and oxygen are usually the ones involved in combustion because of their high electronegativity and the fact that they're very good oxidizers so real is that even though most the time it's oxygen it doesn't always have to be on oxygen  think it through can you describe the different types of chemical ashens  are you able to recognize chemical reactions when they happen you really need to work on that practice I'm sure you pictures going to show you some you need to not only be able to recognize them on paper but in real life also alright chemical reaction practice let's test yourself alright here we have calcium carbonate and is doing what if you look at that you should recognize if that's decomposition hopefully you got that right is barium and hydrochloric acid  and I'm sure you call vet single replacement right then here we have lead nitrate and magnesium sulfate and if you look at that it's level replacement right fishing sulfate and water synthesis oh I hope you recognize this one yes it's combustion that should have been pretty easy dead giveaway alright if you have any questions send an email to Mr cause it mr. Causey. Check out mr. Causey com for PowerPoint videos and much much what is handouts they're worksheets some good stuff don't forget to subscribe to my YouTube channel so you can get the latest on chemistry okay you go do that and happy ions

Uploaded by Laura Houston.

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Chemical Equations: How to Recognize and Classify Chemical Reactions

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