Thursday, May 7, 2009

Moles in an element in a compound?

Ok so thanks to MN Science Teacher I know that to find the amount of moles of copper in copper oxide (CuO):

1. You first find the atomic weights of copper and of oxygen, and add them together. The units for this will be grams per mole.

2. Then take 1.43 grams and divide it by the number you got in step 1. This, then, will be your final answer, and the units in your answer here will be moles. That's all there is to it!

But how do I find the amount of moles of oxygen in the Copper Oxide (CuO). Surely it cant be exactly the same way because then I'll have the same amount of moles of both copper and oxygen in the compound :/


Thanks :)

Moles in an element in a compound?
Since you have the same number of copper atoms as oxygen atoms in CuO, the number of moles of each also has to be equal.
Reply:it's the same. a mole is a quantity, and in every molecule of CuO, you have one Cu and one O. So therefore with 2 CuO molecules, you have 2 Cu's and 2 O's total.

so if you have 2 moles of CuO, you have 2 moles of Cu and 2 moles of O. however many moles of CuO you have is how many moles of the individual elements.

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