If you start with 1.115 g of aluminum, how many grams of alum should be obtained?

Answer 1

How many grams of alum should be obtained? What is alum? Alum is generally a double sulfate salt of aluminum, but there are several different alums. For example, there is chrome alum which is KCr(SO₄)₂, or the more common potassium alum which is KAl(SO₄)₂. We will assume the question refers to the latter form of alum.

Since each mole of KAl(SO₄)₂ contains 1 mol of Al, we can find the moles of alum produced from 1.115 g of Al and then then the grams of Al that this is equal to.

moles of alum formed from 1.115 g of Al:

1.115 g Al x 1 mol Al / 26.98 g x 1 mol alum / mole Al = 0.0413 moles of alum formed from 1.115 g of Al

Convert 0.0413 moles alum, KAl(SO₄)₂ to grams of alum:

molar mass KAl(SO₄)₂ = 258 g/mole

0.0413 moles KAl(SO₄)₂ x 258 g/mole = 10.66 g of alum can be obtained