## stoichiometry

**Anonymous**

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

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

WebElements: the periodic table on the WWW [http://www.webelements.com/]

Copyright 1993-20010 Mark Winter [The University of Sheffield and WebElements Ltd, UK]. All rights reserved.
Martin17 (not verified)| 7 March 2009 - 8:04am## The valency of Al is Al+3

The valency of Al is Al

^{+3}and O is O^{-2}; therefore, you will get Al_{2}O_{3}in order for the +s to balance the -s. O, however, only occurs as O_{2}; therefore to get 3 Os, you need 3 units of O_{2}; that means 6 atoms altogether, so you will end up with 2 of Al_{2}O_{3}. At the same time, you end up with 2 x 2 Al atoms. The balanced equation must be4 Al + 3 O

_{2}> 2 Al_{2}O_{3}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.