00:01
So for the fist -centered cubic, the density equals to the mass of the atoms in a cubic, so the volume of the cube.
00:22
So let's see you have four atom because that is the total number of atoms in the fifth -centered the cube.
00:37
Then you multiply the molar mass, which is one 90 gram per more.
00:47
So that, and then you divided by the avocado's number, so that it will give you the mass of four atoms in a cube.
01:08
So then that is the mass.
01:10
Now you look at the volume.
01:12
Remember that if the radius of the is r, then the cell is square root of 8 multiply r.
01:27
Of course, that should be the cubic.
01:32
But i'm going to try to, because right here, the r is not defined.
01:38
What's the unit? so what if we wanted to do is trying to see that we assume that the unit right here is nanometer.
01:45
If you need to write here as nanometer, i want to convert the nanometer.
01:54
I want to convert the nanometer eventually to a centimeter cubic centimeter, so that on both sides would be the same.
02:07
So first i convert it to the meter, then i convert a meter to the centimeter.
02:18
So that i take power of 3.
02:23
So that will be the total volume.
02:27
Remember, i assume right here, r is a nanometer.
02:33
So now i can finish all these calculations.
02:41
So i'm going to get rid of all the unit, okay? the unit will be canceled...