Question

A silver-copper alloy had a mass of 0.1264g. When the alloy was dissolved in nitric acid and the silver precipitated as silver chloride, the precipitate had a mass of 0.1375g. Calculate the percent of silver in the alloy. For full credit, make sure you show your calculations.

Answer 1

The percent of silver in the alloy is 81.87%.

Step-by-step explanation:

Mass of the alloy = 0.1264 g

Mass of silver chloride precipitate = 0.1375 g

Moles of silver chloride precipitate =
`(0.1375 g)/(143.5 g/mol)=0.0009582 mol`

In 1 mole of silver chloride there are 1 mole of silver, then in 0.0009582 moles of silver chloride will ahve:

`1* 0.0009582 mol=0.0009582 mol` of silver

Mass of 0.0009582 moles of silver = 0.0009582 × 108 g/mol=0.1035 g

The percent of silver in the alloy:

`\frac{\text{Mass of silver}}{\text{mass of an alloy}}* 100`

`=(0.1035 g)/(0.1264 g)* 100=81.87\%`