To calculate the percentage of the mass of the lighter isotope of copper, we need to determine the mass of each isotope and their respective abundances.
Given that the relative atomic mass of copper (Cu) is 63.54, we can assume that it is a weighted average of the two isotopes' masses and abundances.
Let's denote the mass of ⁶³Cu as 'x' and the mass of ⁶⁵Cu as 'y.' We can set up the following equations based on the information provided:
x + y = 63.54 (since the relative atomic mass is the weighted average)
x/y = abundance of ⁶³Cu/abundance of ⁶⁵Cu
Since we're looking for the percentage of the lighter isotope (⁶³Cu), we can rearrange the equations to solve for 'x' and then calculate the percentage.
Solving the equations, we find that x = 63.54 - y, and substituting this into the second equation:
(63.54 - y)/y = abundance of ⁶³Cu/abundance of ⁶⁵Cu
Now, we need the abundance ratio of the isotopes to proceed with the calculation. If you have that information, please provide it, and I'll be able to assist you further in calculating the percentage of the lighter isotope (⁶³Cu).