Comprehensive Guide to Types of Chemical Reactions Explained

in this video we're going to talk about types of chemical reactions synthesis reactions

decomposition reactions combustion reactions and then single and double replacement reactions

so what is a synthesis reaction this is a reaction where you have multiple reactants combining to form a

single product so a plus b turns into a b

let me give you some examples so if we take zinc metal and react it with oxygen gas

this is going to turn into a single product zinc oxide now this reaction is not balanced and we

really don't need to do it for the sake of this video but notice that we have two smaller

components and we're generating a single product that is a synthesis

reaction which is also called a combination reaction

zinc and oxygen are pure elements zinc oxide that's a compound it's made up of two different elements

here's another example if we were to take barium oxide which is a compound

and react it with carbon dioxide which is another compound this will give us a single product at

low temperatures known as barium carbonate this is also a synthesis or combination reaction

because we're taking two smaller components and combining it into a larger product

or a single product so that's the basic idea behind a synthesis reaction

now before we go into the next type of reaction i do want to mention for those of you

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that will be greatly appreciated now let's get back to this video decomposition reactions

a decomposition reaction is the reverse of a synthesis or combination reaction

so in this case you're starting with a single reactant a b and you're going to break it up into two

or more products typically a plus b so a good example of this is magnesium

nitride so this is an ionic compound and when heated

will decompose into its component elements magnesium and nitrogen gas so here we have a single product

breaking down into multiple fragments so that is a decomposition reaction another example

is the use of calcium carbonate if you heat up calcium carbonate you can represent the heat phase with uh

i mean the word heat with a triangle if you heat up calcium carbonate it's going to decompose into calcium oxide

and gaseous carbon dioxide so that's another example of a decomposition reaction it's simply the

reverse of a synthesis reaction the third type of reaction that we need to talk about

is a combustion reaction combustion reactions typically involve some compound containing carbon hydrogen

and or oxygen and typically the most common example of these reactions is that you take that

compound react it with oxygen gas and you're going to get two products carbon dioxide and water

so here's an example of one propane c3h8 reacts with oxygen gas

to produce gaseous carbon dioxide and liquid water depend on the

temperature if the temperature is above 100 that's going to be steam so

we'll put h2o with a gaseous phase another example would be ethanol c2h5oh so this is an example of a compound

containing carbon hydrogen and oxygen when ethanol reacts with oxygen gas it too

can create carbon dioxide and water assuming there is sufficient oxygen gas

to react with it in the first place otherwise carbon monoxide could be created as well which is

not a good gas to deal with but with sufficient oxygen gas this reaction

will go to completion and you'll get carbon dioxide and water so those are examples of combustion

reactions combustion reactions are very exothermic which means they release a lot of

thermal energy when you react gasoline with oxygen let's say in a combustion

engine it will generate a lot of energy a lot of heat energy and some of that energy

is used to power the car to make it move forward and so combustion reactions are very useful in terms of

everyday applications now let's move on to the next type of reaction

that we need to consider and that is single replacement reactions in a single replacement reaction

you have the general formula a plus bc turns into ac plus b so what happens is in this example

a displaces b out of the compound

and so b leaves it's now by itself so let me give you an example in this case

for this type of chemical reaction you're going to have a metal displacing another metal out of a compound

so zinc metal reacts with copper chloride that is aqueous copper chloride which means it's dissolving water

to produce aqueous zinc chloride plus copper metal

so notice that zinc displace copper out of the solution so now zinc is in the solution copper

is now a metal a solid metal that is not dissolved in the solution anymore and so that is a single replacement reaction

zinc replaced copper out of the solution or kicked it out of the solution if you

want to say that now there's another type of single

replacement reaction in this example we considered a metal replacing another metal

you can also have the situation where a non-metal replaces another nonmetal the general reaction for this type of

situation is going to be a plus bc

and that's going to turn into ba plus c

so in this example a let me use a different color

a is going to displace c out of the solution so here's an example

let's say we have a liquid bromine in its elemental form and we're going to react that

with a solution of sodium iodide in this reaction notice that bromine

and iodine or in this case it's in the form of

known as iodide both of these are non-metals bromine and iodine are they're not metallic

so bromine is not going to displace sodium because sodium is a metal bromine is going to displace another

non-metal like itself in this case iodine so we're going to get is sodium bromide

which is an aqueous form plus elementor iodine which is a solid

so in this case we have a non-metal displacing another nonmetal out of the solution

that's the second type of situation that you'll see when dealing with a single replacement

reaction now the next type of reaction we need to consider is a double replacement

reaction in this reaction we have a b reacting

with cd now what are the products that you think we're going to get

and notice the keyword double replacement the two middle ones

will come together that's b and c but it's going to be written as cb not bc and the one

the two parts that are on the outside they're going to pair up together

and it's going to produce a d so those are the products of a double

replacement reaction let me give an example aqueous calcium chloride

reacts with aqueous

sodium nitrate to produce

aqueous calcium nitrate plus aqueous sodium chloride

so this is an example of a double replacement reaction we can see that calcium paired up with

nitrate in this case this would be ad i have them switched around for some reason

and uh sodium paired up with chlorine

as we can see nacl so notice that na is written first this is actually cb

cl is written later if you break this up into ions you'll have calcium two plus you have the

chloride ion na plus and the nitrate ion notice that the

positive ions are written first so that's why sodium is written before

chloride because it has the positive charge calcium

doesn't want to pair up with sodium because like charges repel that's why calcium

pairs up with nitrate because they're opposite charges calcium has a two plus charge nitrate has a

minus one charge ions with opposite charges will attract each other and that's why sodium is

attracted to chloride because they have opposite charges so you shouldn't see calcium paired up

with sodium they have the same charge that's not going to happen and you shouldn't see

chloride paired up with nitrate that's not going to be correct now there are some other types of

displacement reactions or rather double replacement reactions that you need to be familiar

and some of these have special names consider this one let's say if we react calcium nitrate

with sodium phosphate both of these compounds are in

the aqueous phase which means they dissolve in water they're water soluble

now this is going to produce sodium nitrate which also dissolves in water

plus calcium phosphate now calcium phosphate is not water

soluble it is insoluble in water which means it doesn't dissolve in water

now this reaction will be visible the other reaction is not visible because everything was in

the aqueous phase but for this one notice that we get a solid product whenever you mix

two aqueous solutions and if it produces a solid product then the double replacement reaction has

another name and that name is a precipitation reaction calcium

phosphate precipitated out of the solution so this is an example of

a precipitation reaction you may learn this later if you haven't learned it already but

at least now you know what it is here's another one if we take

sodium sulfide in its aqueous phase and react it with hydrochloric acid

this is going to create sodium chloride which will also be an aqueous phase but we'll also get something at excuse

me something else h2s hydrosulfuric acid

and this is a gas so notice that not everything is in the aqueous phase we're mixing two

aqueous solutions and we're getting not a solid product

but a gaseous product so this type of reaction even though it

is a double replacement reaction sodium paired up with chlorine hydrogen paired up with sulfur

even though it's a double replacement reaction it's it also has another name and

that name is known as a gas evolution

reaction because a gas evolved out of the solution

so that is a gas evolution reaction another type of double replacement reaction

and for those of you who are curious there is another type of double replacement

reaction and here it is let's say we react hydrochloric acid

with sodium hydroxide in this example sodium will pair up with chlorine

forming table salt sodium chloride and then hydrogen is going to pair up with hydroxide

forming water now water is not a solid it's not a gas but it's a liquid

so what do you call this this is still a double replacement reaction but it also has another name

and the name for this reaction is an acid base

neutralization reaction why is it called that

well hcl is an acid hydrochloric acid sodium hydroxide is a very strong base

whenever you mix an acid and a base specifically a strong acid and a strong base

they will neutralize each other creating salt and water and that's all folks that is the end of

this lesson so for those of you who found it to be helpful and uh very informative

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so thanks again for watching and i'll see you hopefully in the next video