We’re being asked to determine the **number of Al atoms in a unit cell of spinel**.

Spinel is a mineral that contains 37.9% Al, 17.1% Mg, and 45.0% O, by mass, and has a density of 3.57 g/cm^{3}. The unit cell is cubic, with an edge length of 809 pm.

Recall that mass precent formula is given by:

$\overline{){\mathbf{mass}}{\mathbf{}}{\mathbf{percent}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}\frac{\mathbf{mass}\mathbf{}\mathbf{component}}{\mathbf{total}\mathbf{}\mathbf{mass}}{\mathbf{\times}}{\mathbf{100}}}$

We will do the following steps to solve the problem:

Step 1: Calculate the mass of Al

Step 2: Calculate the number of Al atoms

Spinel is a mineral that contains 37.9% Al, 17.1% Mg, and 45.0% O, by mass, and has a density of 3.57 g/cm^{3}. The unit cell is cubic, with an edge length of 809 pm.

How many atoms of Al are in the unit cell?

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Unit Cell concept. You can view video lessons to learn Unit Cell. Or if you need more Unit Cell practice, you can also practice Unit Cell practice problems.