allesy5dmprincri
Answered

Lithium has two isotopes.

Li-6 and Li-7.

Li-6 mass = 6.015121amu

Li-7 mass = 7.016003amu

Lithium Mass = 6.94049amu


What is percent abundance of Li-6?


I know that there is an equation:

6.9409 = (% Abundance Li-6 Weight of Li-6) + (% Abundance Li-7 Weight of Li-7)


I don't know how to use it.

Verified Answer :

Hagrid

This is in the assumption that these are the only 2 isotopes. This means that:
abundance of Li-6 = X
abundance of Li-7 = 1-X

Hence from your equations 
6.9409 = (X  6.015121amu) + ((1-X)  7.016003amu)
Solve for X = 0.075 or 7.50%

goldfox12

Answer: This is in the assumption that these are the only 2 isotopes. This means that:

abundance of Li-6 = X

abundance of Li-7 = 1-X

Hence from your equations

6.9409 = (X 6.015121amu) + ((1-X) 7.016003amu)

Solve for X = 0.075 or 7.50%

Explanation:

Related Questions