00:02
Hi there.
00:03
In this question, we are asked to calculate the atomic mass of carbon.
00:07
The atomic mass is actually an average atomic mass, and it is not a straight average.
00:13
It is a weighted average.
00:17
A weighted average means that we need to take into account the relative abundance of each of the isotopes.
00:26
You are perhaps most familiar with weighted averages in the calculation of grades.
00:30
Perhaps your teacher counts quizzes or homework is 20%, quizzes is 30%, and tests as 50%.
00:38
Well, you know that you cannot just take all of your scores and do a straight average if that is the case.
00:43
You have to take an average for each of those categories and then add those values together.
00:49
So that's what we need to do here.
00:52
We need to take the percent abundance, multiplied times the mass for each isotope.
01:04
And then we're going to go ahead and add those products together.
01:09
So there are only two isotopes here...