Sign up for our free STEM online summer camps starting June 1st!View Summer Courses

### Determine the formula weights of each of the foll…

00:28
Auburn University Main Campus

Need more help? Fill out this quick form to get professional live tutoring.

Get live tutoring
Problem 22

Balance the following equations and indicate whether they are combination, decomposition, or combustion reactions:
$$\begin{array}{l}{\text { (a) } \mathrm{PbCO}_{3}(s) \longrightarrow \mathrm{PbO}(s)+\mathrm{CO}_{2}(g)} \\ {\text { (b) } \mathrm{C}_{2} \mathrm{H}_{4}(g)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)} \\ {\text { (c) } \mathrm{Mg}(s)+\mathrm{N}_{2}(g) \longrightarrow \mathrm{Mg}_{3} \mathrm{N}_{2}(s)} \\ {\text { (d) } \mathrm{C}_{7} \mathrm{H}_{8} \mathrm{O}_{2}(l)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)} \\ \text { (e) } \mathrm{Al}(s)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{AlCl}_{3}(s) \end{array}$$

a) See explanation for answer.
b) See explanation for answer.
c) $3 \mathrm{Mg}+\mathrm{N} 2 \ldots \mathrm{Mg3N} 2$
Combination reaction
d) See explanation for answer.
e) See explanation for answer.

## Discussion

You must be signed in to discuss.

## Video Transcript

So this problem we have to balance some relation equation, and we have to say whether there, um combination or decomposition are compassion creation. So before we balance variations, this no. First, what are the combination decomposition and compassion reactions? So combination relation is a type of reaction in which two dorm or substances combine to either to farm one product. So, for example, if a and B R two substances and the reactor form and other substance see, then this reaction is called a combination, and then the composition is just the opposite. Creation of this combination relation in with one substance decomposes two. I had to make her toe produce two or more substances. So in this reaction is decomposed to produce B and C. And that's why this consideration are called decomposition. Relation and the conversion reaction are basically those relations, which involves creation off in his substance with oxygen. So, for example, if is reckoned with oxygen, then this is called compassion creation and in the compassion reactions of hydrocarbons. We always get sealed, too, and it's too as product. So these are two different types off reactions here, starting in this chapter. Now let's go to the creation equations and then balance and as sign any of the relation ripe to those reactions. So the first one here we have is let covenant. It's forming lead oxide and carbon dioxide. So, as you know, to balance referee questions, we follows some simple rules or steps. The rules are first rate. Bella's the maters, then a balance, the non metals. Then we balance hide Rosen's. And finally we Bannon's oxygen. Okay, so, hear what we'LL do is well right. It's business we have and it's signed. And then we'LL write how many off its basis we have on its side. So you have one laid here, one laid here we have one carbon here, one carbon here. Yep, Three Oaks is in here one plus two, three horses in here. So that means that this creation is already in a balanced a state, and we don't need toe balance it anymore. So the creation itself is a balanced re in fornication. Now, what type of creation is this as we have? You know that in variation in which one substance decomposes to give, um, two or more substances that is called the decomposition relation. And that's what we're seeing and that means this reaction Is there decomposition relation? No, that he'd go to our next to them and pull here, which is in which seat village for Recto It Occean to produce Seo too. And it's tool. So what type of creation is this? Says they have said that the reactions which include all seein as a reactant those are the compassion reactions and in compassion duration ofthe hydrocarbons always get sued twenty each toe. That means without a doubt this reaction is a compassion reaction. Now let's balance duration equation in first, right, Donald, the species we have here in both side see, So we'LL always write them in order we will banish them And as you have said that first rebalance medals then non metals, then hydrogen and oxygen and saying there is no metal will start with our non metal, which is carbon. So we have two carbon reactant side and we have forehead risen to oxygen the product side again we have one Carbon two had risen three oxygen. Now we have took our win our reactors side But we have one carbon in our peroxide They're so I will places to as a coefficient forthis carbon dioxide tohave two carbon in the products that also but in the at the same time, we're changing the number. Foxes there. Now we have two times two four plus one five oxygen here, Daniel. Balance or hide Risen. Since we now have our the number of carbons, balance, balance or high treason, we have four hundred in the reactor site, but two hundred in the projects sign. So what will do? We will place it to hear to get four hydrogen in the product side also. But at the same time, we're increasing the number of oxygen by one that Mr Tibbs tow for us. True that, Miss, we now have six oxygen in the peroxide. So now we have a carbon and hydrogen. Bella? No. We balance our oxygen. So the product side, we have six oxygen reaction said we have to. So we need six oxen in the reactor inside also. And we can get that by simply putting three here, which will give us six oxygen in the reactor inside. Also. So now we have our number of carbons. Balance number of high treason balanced a number of oxygen balance that This is our balanced reaffirm equation, which is a compassion reaction. No, I moved toward next example. Where we him Magnus reacting with nitrogen gas to produce empty tree in two. Okay, so what kind of reaction is thiss from here? You can easily say that true substances air combining reacting together to form one product and from the from the definitions to given here you can see that this is a combination type creation. So this is a combination reaction. Now what we do is we will balance duration. So you're magnificient and night risen. And the reaction is sign and we have one magnificient to imprison the reactor's side and treem ignition do nitrogen in the porter's sign. So what we'LL do you first have to balance our ignition. So since we have three mag nation in the product sign Well, put it three here to have a premonition. The reaction side also And then so that's how we are. So now we have three magnification on its side and we have tonight Wasn't it signed that miss this's are balanced equation for this reaction and I move to our next example where we have see seven eight orto No, really, with oxygen gas to produce you too, and is too. So again says this relation in worlds, oxygen as a react and And from here we can see that board up, sir. C o twenty each tool which are obvious product for the ah, compassion off hydrocarbons. That means this is a compassion reaction. And now we will balance this reaction. We have carbon, hydrogen, oxygen, carbon, hydrogen and oxygen. Then we have seven high treason. Seven carbon in the reactor. Inside, we have eight hatreds and and two plus two four oxygen peroxide. We have one car one We have to press one. Oh, we have to had risen Andi two plus one Our tree occean. So first real balance A number of carbons since you have seven. Cameron, the reactor sign. We need seven covering the correct several, son that for the trees. And we just for the seventies before this year too tohave seven carbon in the reactors are seven covering the product side also and we're also adding more oxygen. Now we have seven times to fourteen percent fifteen oxygen in the perros side, Then we'll Bannon. So a number of hydra is and we have eight hundred in the reactor side but going the peroxide so we will multiply these by four toe have eight hide risen in the product side also okay And finally and now says we're also multiplying this box the oxygen also with his four. That means we now have four plus seven times to fort in total eighteen oxygen here. So now we need eighteen oxygen in the reactors are also so we have to hear and we need sixteen more and we can do that just very simply multiplying these by eight which delivers a Thames to sixteen plus two total eighteen oxygen. So now we have our number of carbon bananas. Number of high treason, Valentina, more boxes and ballon. That means this's our balanced reaction equation for this creation. And finally we have aluminium reacting with chlorine gas. Peru's l Seal three. Okay, so now again. So since here two substances are reacting or combining together to produce one correct, that is a combination relation and the balance this rationing question first, will Banisar number off metal. So here we have a hell of a name is the metal. We have one element on his side. That means aluminium is balanced now, but we have no clue in the reactor inside and three cloning the peroxide. And if we want to balance the number of glory is what we have to do is we have to find out the list goes on multiple off two and three, which is six. That means we need six glory on each side. And for that we'LL multiplied thiss chlorine by three toe. Get six chlorine in the design and we will multiply this by to forget two times two six glowing in the And they said also. But now, since we have also changed in our fellow medium, which is now on the peroxide, that must win it to eliminate the reactor side also. So now we have will two aluminium on its side and we have six chlorine on its side. That was this's our balanced equation for this reaction.