Question
Thu January 03, 2013 By:

How many aluminum ions are present in 0.51 grams of Aluminum Oxide?

Expert Reply
Sat January 05, 2013
Write the chemical formula : Al2O3
Calculate the number of moles for aluminum oxide.
You should know the formula which is the mass given (0.51g) divided by the Mass of aluminum oxide. Mass of 1 mole Al2O3 = 102 g.
So, n = 0.51 /102 g = 0.005 = 5 x 10-3
Since there is '2' moles of Aluminium per mole of Al2O3 you multiplly the number of moles calculated for aluminum oxide by 2.

Number of Al2O3 molecules in 5 x 10-3 mole = (6.032 x 1023)x( 5 x 10-3) = 30.115 x 1020

Number of aluminum ions per molecule = 2.

Number of aluminum ions in mole Al2O3 =30.115 x 1020 x 2 = 60.23 x 1020

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