00:02
Hi there.
00:03
In this question, we are given the percentage composition of this compound, and we are asked to determine its empirical formula.
00:11
So let's write down the information that we know.
00:14
We have 5 .42 % hydrogen, 64 .56 % carbon, and 30 .02 % iron.
00:38
And to determine the empirical formula, we need to figure out the number of moles of each of these.
00:44
So that we can compare those moles to find that smallest whole number ratio, because that's what an empirical formula is, is the smallest whole number ratio.
00:53
So what i am going to do is these percents are true regardless what size sample you have.
00:59
I am going to assume a 100 gram sample, and the reason for that is when i assume a 100 gram sample, it makes my math in this next step very easy, because i want to see how many grams in this one, 100 gram sample are due to each of these elements.
01:19
So if we have 5 .42 % hydrogen, that's going to be 5 .42 grams of hydrogen in this 100 gram sample.
01:30
So in other words, i selected a 100 gram sample because therefore i can just change my percent signs to grams.
01:38
So remember i'm trying to get to moles.
01:41
So if i start with grams, then i can divide by each element's molar mass to get to moles.
01:47
So let's go ahead and do that.
01:49
Hydrogen is 1 .008 grams from the periodic table in every mole of hydrogen.
01:58
This gives me 5 .38 moles of hydrogen.
02:07
For carbon, carbon's molar mass is 12 .01 in every mole of carbon...