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Types of Reactions - Concept

Teacher/Instructor Kendal Orenstein
Kendal Orenstein

Rutger's University
M.Ed., Columbia Teachers College

Kendal founded an academic coaching company in Washington D.C. and teaches in local area schools. In her spare time she loves to explore new places.

Scientists classify different types of chemical reactions using their behavior. Types of reactions include single displacement, double displacement, synthesis, decomposition and combustion.

Alright there're many types of reactions that there are in the world, and in class you probably list 5 main types of reactions we're going to have to know okay. And you're probably going to have to predict the products of those reactions when you see just the reactant. So let's figure out how we're going to about doing this, okay I listed up here all the 5 different types of reactions that you're going to see in class okay. And we have hints on how I can figure out which one is which okay. So you have synthesis reaction, synthesis is another way of saying I'm making something, I'm synthesizing something. We're just going to make one product, so anytime you see one single product you know automatically synthesis okay.

Next type of reaction we have is decomposition, when something decomposes when one thing decomposes into several things. So that's thing, that's one reactant anytime time you see one reactant you're going to know in your head decomposition. Next type of reaction is single replacement reaction and the way that you recognize that is if you have an element and a compound, always the compound will be an ionic compound it's going to produce another element and another compound okay. So that's a single replacement reaction, double replacement reaction is 2 ionic compounds coming together and switching partners okay. So if you notice that compound plus compound yielding another compound plus another compound they're going to nail in your head double replacement reaction 2 things with switching places.

Lastly you're going to have the combustion reactions, combustion reactions are the easiest. They are hydrocarbon reacting with oxygen to produce, these are always your products carbon dioxide and water that is the most typical form of a combustion reaction. But don't forget anything that reacts with oxygen gas will also be classified as combustion. Alright so let's take this into action, alright so let's say we have the reactant silver nitrate and potassium phosphate let's out those in equation form. Let's say if silver nitrate which you know as a plus 1 charge, nitrate is a minus 1 charge so silver nitrate AgNO3 plus potassium phosphate, potassium is a plus 1, phosphate is a minus 3 so we're going to say K3PO4 and they are 2 compounds. These are 2 ionic compounds, so you're alright which one is it? Are you going to look at your reactions and say double replacement, so I'm going to write DR just to make it simple okay. And we're going to figure out the products for these, so we remember that they just switched partners okay, so the metal is going to go with the new non-metal in this case PO4 and K is going to bond with NO3. So we're going to have Ag is a plus 1, PO4 is a minus 3 so we're going to have Ag3PO4 plus K is a plus 1 NO3 is a minus 1 KNO3.

Don't forget to, don't worry about the subscripts in this, we'll take of that when we balance it which is right now. So we have 3 silvers on this side we need 3 silvers on this side, we have 1 nitrate on this side, 1 nitrate, 3 potassium this actually is balanced. 3 silvers, 3 silvers, 3 potassiums, 3 potassiums, 1 phosphate, 1 phosphate, 3 nitrates, 3 nitrates yeah 3 nitrates perfect okay so this how we can identify this is double replacement reaction. Let's go to another one, let's say we have potassium carbonate, something should be digging off in your head. This is a single reactant, single reactant what is that? That's going to be decomposition, so we're going to just put decomp, I know in my head this is decomposition. So potassium carbonate, most of the time we're not going to predict these type of reactions, they're very difficult to predict or I'll just write this out for you potassium carbonate is K2CO3 and this is actually going to break down into K2O+CO2 and this is actually pretty difficult to actually predict the product but in most skill that you're going to need is going to be able to identify this as a decomposition reaction.

Let's get to the next one, we have butane plus oxygen, oxygen cling, cling, that should ding something off in your head combustion reaction. And notice also butane is a hydrocarbon, you might not know that butane is a hydrocarbon but I'll let you know that butane is C4H10 hydrocarbon plus oxygen gas we know oxygen is O2 and it always, always forms CO2+H2O that's easy, easy, easy, this is a combustion reaction okay. Next one we have is sodium iodide and bromine, we have an ionic compound coming together with an element that should ding in your head as okay that is a single replacement reaction I'm just going to put SR. So what's going to happen is this non-metal is going to replace this non-metal. Don't forget that non-metals replace non-metals and metals replace metals. So we're going to have sodium iodide plus bromine gas is going to yield, these are going to replace each other so iodide is not going to be its own, don't forget iodine is a diatomic so it's going to be I2 plus NaBr okay.

I haven't balanced this one or this one I'm just going to save that for another time, I just want to make sure that we understand how we get these products and be able to identify what type of a reaction this is. But I did want to note that these are not balanced yet. Hydrogen and chlorine coming together, we have H2 because don't forget hydrogen is a diatomic and chlorine Cl2, chlorine is also a diatomic they're 2 elements coming together and the only thing they can possibly do is make a single product HCl and what kind of a reaction is that? When there's a single product that is a synthesis reaction, or combination reaction whichever one your teacher uses yeah okay. So hopefully this tends to help you in predicting the actual products of reactions and also the different types of reactions that you're going to see.