stoichiometry

I need help with my stoichiometry homework. the problem says.. 54.0 grams of aluminum react with oxygen. how many grams of aluminum oxide are produced? if anyone could show me how to do the problems thanks...

Scott

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The valency of Al is Al+3

The valency of Al is Al+3 and O is O-2; therefore, you will get Al2O3 in order for the +s to balance the -s. O, however, only occurs as O2; therefore to get 3 Os, you need 3 units of O2; that means 6 atoms altogether, so you will end up with 2 of Al2O3. At the same time, you end up with 2 x 2 Al atoms. The balanced equation must be

4 Al + 3 O2 > 2 Al2O3

Now multiply the atomic weight of Al by 4 and the atomic weight of O by 6. Add these together and you will get twice the molecular weight of alumina; 54 will be a ratio of the weight of the 4 Al units and apply that ratio to the weight of each member of the balanced equation.

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