Question

An alloy of gold and silver contains 38.5% silver by mass and has a density of 14.6 g.ml–1. what is the molar concentration of silver in this alloy

Answer 1

The molar mass of Silver (Au) is 107.86 g-mol.

Now, lets first convert the g into ml using density.

The alloy contains 38.5 silver by mass which means it contains 38.5% w/w of silver. Simply put, 100 g of the alloy contains 38.5 g Au.

Density of the alloy is 14.6 g/ml which means 100g of the alloy equals 100/14.6 = 6.85 ml.

Now, to get the molar concentration, we first get the total mass of Au present in 1000 ml of the alloy and then divide it by the molar mass given above (first line).

Molar concentration = [(38.5/6.85)*1000]/[107.86] = 52.1 M