00:01
All right, so we have eight chemical compounds here, and we're going to find the mass percent of each element in each of these compounds.
00:15
Okay, so the overall formula we're going to use to find mass percent is taking the mass of each element, so mass of the element and e, and dividing it by the total mass.
00:35
One mole of compound, right? so we always assume one mole of compound, one molar compound.
00:55
All right, so we haven't given us any like moles or mass or anything of these compounds, but we already know that we are working with one mole of each compound and we can easily calculate the molar mass.
01:15
And we know that mass is equivalent to moles multiplied by molar mass.
01:23
All right, so let's get started.
01:26
So first off, we have calcium phosphate.
01:30
Okay, let's start off by listing all the elements present here.
01:37
We have a calcium, phosphorus, and oxygen, right? mm -hmm.
01:53
Okay.
01:53
So let's first calculate the m .e.
01:58
The mass of each element, the mass of one mole of each of these elements.
02:06
Oops.
02:09
So we're going to use this formula.
02:11
We're going to do moles multiply by molar mass.
02:15
So in one mole of calcium phosphate, we have three moles of calcium.
02:21
So we must multiply three, like halcym's molar mass, which is around 40.
02:34
Right.
02:35
In here, in one mole of calcium phosphate, we have two moles of phosphorus.
02:42
So we're multiplying moles, but molar mass, 30 .9.
02:53
And likewise, we have eight moles of oxygen.
03:01
Yeah, just gonna call it 16.
03:15
Right? so now we're going to sum up these numbers, which will then, you know, give us what our total is, our total mass, which is 310 .18.
03:46
All right, so the number i'm getting here is if i already have included more sick fix, like written here, but you don't have so much time for me to be waiting all these figs.
04:01
You have eight questions of these to go.
04:04
So now what we're going to do to find the mass percent of each element is we're going to take this number and divide it by the total over here.
04:17
Sorry about that.
04:20
Okay.
04:22
So this column is the mass percent.
04:27
So three times 40.
04:31
Is 120.
04:34
120 divided by 310 basically is equivalent to 38 .8%.
04:50
Right? okay, so that's how we're going to do it for calcium.
04:55
Now, same thing for phosphorus.
04:58
We take this mass and divide it by the m total, which will give us 19 .9%.
05:20
19 .9%.
05:21
Oh wow.
05:27
And for oxygen, we'll multiply this mass divided by the total, which will give us 41 .3%.
05:43
That's how we'll do it for the remaining.
05:49
Okay.
05:50
Let me go over it one more time.
05:52
Now this is working.
05:53
So we take cadmium.
05:59
We will just list down each element, right? there's going to be an addition that we're about to do.
06:10
I'm going to use this formula here.
06:13
Take moles of element and multiply by the molar mass of the element, assuming one mole of compound.
06:21
So on one mole of compound, we have one mole of cadmium.
06:27
Cadmium's molar mass is 112 .411.
06:35
We have one mole of sulfur, and sulfur's molar mass is 32 .066.
06:44
And we have 4 moles of oxygen.
06:47
And oxygen's molar mass is 15 .994.
06:52
Which rounds to 16.
06:54
And if we sum this up, including all the sig -figs, or more.
06:58
More digits.
06:59
We get 208 .47 and this is the mass total.
07:09
Now we're just going to take each of these masses and divided by the mass total to find mass percent.
07:23
So mass percent is going to be in this column.
07:27
What is that happening? okay.
07:36
Like right.
07:40
So 121 or sorry, 112.
07:45
Divided by 208 equals 53 .9%.
07:55
That's a 5.
07:58
Next, first off, for 32 over -trongeon 8 will give us 15 .4%.
08:08
And lastly, for oxygen, 4 multiplied by 16, then divided by 208, will give us 30 .7%.
08:18
Okay.
08:19
Now that we have understanding of how this works, we're going to move a bit faster.
08:26
And next up, we have iron three sulfate.
08:30
We'll just quickly list out each element.
08:37
Now calculate the masses.
08:43
Okay.
08:46
So we have two moles of iron.
08:50
An iron's molar mass, 55.
09:00
Don't forget, we need to multiply through this bracket...