We’re being asked to determine the number of atoms of zinc in a fitting containing 37.0 % by mass Zn.
We know that the fitting is a common brass alloy composed of copper, Cu and Zinc, Zn.
And to do that we're going to do the following steps:
Step 1: Solve for mass of the common brass fitting (solution) using the volume and
density of the fitting.
volume solution (density) → mass solution
Step 2: Solve for mass of Zinc using the mass percent formula shown below:
Since we are dealing with an alloy (solid solution), we can rewrite the equation as:
Step 3: Solve for moles of Zn in fitting and # of atoms of Zn using Avogadro's number
Common brass is a copper and zinc alloy containing 37.0% zinc by mass and having a density of 8.48 g/cm3. A fitting composed of common brass has a total volume of 120.5 cm3 .
How many atoms of zinc does the fitting contain?