Question

Consider an alloy that is 13.5% copper by mass in tin. Copper makes up what percentage of the atoms in this sample?

Please show work.

Answer 1

an alloy contains 13.5% copper by mass

Molecular mass of copper = 63.546

Molecular mass of tin = 118.71

we will calculate for 100 gm alloy (13.5 f Copper + 86.5 g tin)

Moles of copper in 100 g alloy = 13.5/63.546 = 0.212444 Mole

no of atoms = 0.212444 x 6.023 x 10²³ = 1.28 x 10²³ atoms

Moles of tin in 100 gm of alloy = 86.5/ 118.7= 0.728728 Mole

no of atoms = 0.728728 x 6.023 x 10²³ = 4.389 x 10²³ atoms

percentage of atoms = .28 x 10²³ x 100 / 4.389 x 10²³ = 29%