A compound composed of only carbon and chlorine is 85.5% chlorine by mass. Propose a Lewis structure for the compound.

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Welcome back everyone to another video, a compound composed of only carbon and chlorine is 85.5% chlorine biomass, propose a Lewis structure for the compound. And we are given for answer choices ABC and D those are just different lowest structures that we can get. We want to determine which one is the correct one. We're going to solve this problem assuming that the starting mass of our compound is 100 g. And this will be efficient because now we can say that this compound corresponds to the mass of chlorine equivalent to 85.5 g. And therefore the remaining 14.5 g belong to carbon. Now, if we use those masses, we can get the number of moles of each. And the reason why we need moles is simply because we want to find the ratio of our atoms in the structure. So we're going to start by calculating the number of moles of chlorine, taking 85.5 g and dividing by the molar mass of chlorine, which is 35.45 g per mole. So in this case, if we do the math, we get 2.41 moles. And if we calculate the number of moles of carbon, we take 14.5 g of carbon and divided by its smaller mass, which is 12.0 or 1 g per mole. In this case, we get 1.21 moles. Now, what is the ratio here? Well, essentially we find the lowest number, that'd be 1.21 and we divide both numbers by the lowest one. So we can say that the ratio of the number of moles of carbon and the number of modes of chlorine would be 122, right? Because we essentially divide both numbers by 1.21 we get one and two respectively. So the empirical formula which shows us the ratio of atoms will be C cl two right? And the molecular formula would have N which corresponds to the number of the emir units, right. So now let's think how we can actually get a possible molecular formula from here. Well, if we only take one carbon and bonds two chlorine atoms, the problem here is that carbon does not have an octet. Of course, we have to remember that each chlorine must have we alone pairs to have an octet, but carbon doesn't have an octet, right? It only has two bonds, it must have four bonds in total. So the only way for us to get a molecular formula is to take an end value of two such that we got two carbons and four chlorine atoms. So we can actually bond another carbon, right? And two chlorine atoms to that carbon. Once again, let's fill our long pairs for each chlorine. And now let's think about the two carbons bonded to each other. Well, we don't want to have any L pairs on those carbons, but we have to remember that the valency of carbon is four. So the way to fix this formula is actually to introduce a double bond between the two carbon atoms, which allows us to get a complete and crack Louis structure. For this compound. We can clearly see based on the answer choices that the correct option to this problem would be option B. So let's go ahead and label it as the correct answer. B is the crack Louis structure to this problem. Thank you for watching.

A compound composed of only carbon and chlorine is 85.5% chlorine by mass. Propose a Lewis structure for the compound.

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Key Concepts

Empirical Formula

Lewis Structures

Valence Electrons