00:03
Hi there.
00:03
In each of these questions, we are given a number of moles, and we're trying to convert to number of molecules.
00:17
Well, any time we're trying to convert from moles to a number of particles, we need to use avogadro's number.
00:25
Avagadro's number gives us the number of particles in one mole of anything.
00:31
So in one mole of these substances, there are going to be 6 .02 times 10 to the 23rd molecules because 6 .02 times 10 to the 23rd is avogadro's number, the number of molecules in one mole of a substance.
00:51
All right, so let's go ahead and calculate our answer for each of these, using that equality as our conversion factor.
00:59
We have 5 .3 moles of the penicillin, so we need to use avogadro's number.
01:08
So that equality, we're going to write it as a conversion factor.
01:12
I want the mole in the denominator, so that mole will cancel, which means 6 .02 times 10 to the 23rd molecules needs to go in the numerator.
01:25
The unit mole will cancel, multiplying 5 .3 times off a goddra's number, and rounding to two significant figures as directed, gives us 3 .2 times 10 to the 24th molecules of the penicillin.
01:46
All right...