Question

Assume the atomic mass of element x is 22.99 amu. A 22.42 g sample of x combines with 34.56 g of another element y to form a compound xy. Calculate the atomic mass of y

Answer 1

The formula of the compound is xy.

This means that one mol of x combines with one mol of y. The proportion is 1:1

The number of moles in 22.42 g of x is equal to this weight divided by its atomic mass: #  moles of x = 22.42 g / 22. 99 g/mol = 0.975207

Then the number of moles of y is the same and you can calculate the atomic mass by dividing the mass by the number of moles:

aomic mass = weight in grams / # of moles = 34.56 g / 0.975207 mol = 35.44 g/mol = 35.44 amu.