Question

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 116.5 cm3

How many atoms of copper does the fitting contain?

How many atoms of zinc does the fitting contain?

Answer 1

Total Volume of Common Brass = 116.5 cm³

Density of Common Brass = 8.48 g/cm³

Total Mass of Common Brass = 8.48 x 116.5 = 987.92 g

Mass of Zinc in common brass = 0.37 x 987.92 = 365.5304 g

Moles of Zinc in common brass = 365.5304 / 65.38 = 5.591

Atoms of Zinc in the Fitting = 5.591 x 6.023 x 10²³ = 3.367 x 10²⁴

Mass of Copper in common brass = 987.92 - 365.5304 = 622.3896 g

Moles of Zinc in common brass = 622.3896 / 63.546 = 9.794

Atoms of Zinc in the Fitting = 9.794 x 6.023 x 10²³ = 5.899 x 10²⁴