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.

Question

Chemistry

Drew Brown

23 November, 22:27

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.

+5

Answers (1)

Know the Answer?

Rachel French · Answer 1

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%

Lithium has two isotopes.Li-6 and Li-7.Li-6 mass = 6.015121amuLi-7 mass = 7.016003amuLithium Mass = 6.94049amuWhat 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.