I am facing a mathematical problem in chemistry: Suppose we have two atoms X and Y , each has two isotopes (forms of the same atom with different masses)
(X1) mass = 12 (units) and represents 90% of the X atom forms in nature (its abundance in nature)
(X2) mass = 11 (units) and represents 10% of the X atom forms in nature (its abundance in nature)
(Y1) mass = 3 (units) and represents 85% of the X atom forms in nature (its abundance in nature)
(Y2) mass = 4 (units) and represents 10% of the X atom forms in nature (its abundance in nature)
So, average mass for X atom = [(X1 mass * X amount in nature * X1 abundance) + (X2 mass * X amount in nature * X2 abundance)] / (X amount in nature)
, and Y the same way
Now if we have a compound that contains 3 atoms of X bound to 2 atoms of Y, then what will be the average mass of the compound? It is expressed in Chemistry books as : 3average mass of X + 2Average mass of Y
What is the prove that yield the last equation ?