00:01
If i have one gram of chromium, and i want to know how many moles is, i'm going to need the molar mass of chromium.
00:09
I'm going to think of it as 51 .99 grams in one mole.
00:16
So i have one gram of chromium.
00:22
And for every one mole of chromium, i have 51 .99 grams.
00:29
It stands to reason that i should have a very small amount of chromium.
00:33
Chromium, 1 divided by 51 .99 is equal to 0 .0192 moles of chromium.
00:46
And i can see that my units cancel out and that's why i get moles.
00:52
Next we have chlorine gas.
00:57
So that has a formula of cl2.
01:01
In order to find the molar mass of co2, i need to use twice as many chlorine gas.
01:08
Chlorine atoms, 2 times 35 .45, is 70 .90.
01:22
So i have that many grams in one mole.
01:26
Let me do this a little bit differently.
01:28
I know that i have 1 .00 grams of chlorine, and i want to know how many moles that is.
01:37
I can set up a proportion to figure this out.
01:40
I know that i have 70 .90 grams of chlorine in one mole.
01:45
So i can already see this is starting to look like a proportion.
01:50
I want to know how many moles go into one gram.
01:54
I can set this up, turn this into an equation that i can solve, and i can readily see that x is going to be equal to 1 divided by 70.
02:07
Notice it's the same thing as taking the mass and dividing by the molar mass.
02:13
So 1 divided by 70 .9 is 0141 .1.
02:41
Next, let's look at gold.
02:49
So for gold, i know that the molar mass is 196 .97 in every mole.
03:01
So let me do it the same way i just did it.
03:03
I want to know how many moles are in one gram of gold...