A 10.0000 g block of aluminum is heated and placed in a stream of oxygen gas, resulting in the formation of aluminum oxide on the surface of the block.

Question

A 10.0000 g block of aluminum is heated and placed in a stream of oxygen gas, resulting in the formation of aluminum oxide on the surface of the block. 
The block is cooled and weighed and found to have a mass of 11.6471 g.
The block is then placed in a weak acid to remove the aluminum oxide layer from the block.
After a of the aluminum oxide is removed, the block is weighed and found to have a mass of 8.1471 g.
What is the empirical formula of aluminum oxide?

I know how to do the whole process for finding the empirical formula, but I am confused what is the mass of aluminum and what is the mass of oxygen that we start with?
I need to know this in order to multiply it by the molar mass.

DrBob222 · Answer

I suggest you proof your post and correct the omission of word, or words, "After a ......of the aluminum...."

Dave · Answer

I don't understand what you mean?
I really need to know the values of aluminum and oxygen to solve the problem.
I guessed that Aluminum Oxide is 3.5 g and oxygen is 1.6471 g and Aluminum is 1. Something.