Urgent stoichiometry help - VCAA 2011

[ahat]

Hey guys.

I'm really having trouble understanding why n(P₂O₅) = 0.5 n(P)
Much appreciated if someone could explain this concept, I can't get my head around it.

Thanks.

[lzxnl]

I have 100 apples. I need to distribute them between children and each one wants two apples. The maximum number of children that I can satisfy is half the number of apples I have in total.

Similarly, if you have 100 molecules of P₂O₅, this is like having a hundred children. Each molecule is "holding" two phosphorus atoms. There are 200 phosphorus atoms in total as each molecule has two phosphorus atoms. So the number of  P₂O₅ molecules is half the number of phosphorus atoms.

It's really not that complicated.

[ahat]

Sweet, thankyou.