100g of H2 = ? mol
100g of 1/2O2 = ? mol

help me~!

Dimensional analysis is your friend.
100g H2 x (1mol/2g)
Cancel the units so you get (100 x 1mol)/2=50 mol H2

It's easier to see how to cancel if you write it on paper. If you were to write (2g/mol) units wouldn't cancel and you would get units of grams squared per mol. Doesn't make much sense...Let me know if that helps.

.

how about
32g of O2 = ? mol
32g of 1/2O2 = ? mol
14g of Al = ? mol
14g of 2Al = ? mol

how about
32g of O2 = ? mol
32g of 1/2O2 = ? mol


These two equal each other.
Same thing with Aluminum.

If you have two piles EACH of a kilogram, is it the same as a pile that is 2 kilos?

These two equal each other.
Same thing with Aluminum.

If you have two piles EACH of a kilogram, is it the same as a pile that is 2 kilos?

really? because diff people r telling me diff answers.
Some people said
32g of O2 = 1mol
but
32g of 1/2O2 = 2 mol because it's like saying one O that is 16g/mol.

really? because diff people r telling me diff answers.
Some people said
32g of O2 = 1mol
but
32g of 1/2O2 = 2 mol because it's like saying one O that is 16g/mol.


They're wrong.

Think about it. You have 32 grams of it. That is a set number of grams and hence a set number of molecules and (finally) a set number of moles.
You can't have single atoms of Oxygen floating around anyway.

They're wrong.

Think about it. You have 32 grams of it. That is a set number of grams and hence a set number of molecules and (finally) a set number of moles.
You can't have single atoms of Oxygen floating around anyway.

So far, 2 people said 32g of 1/2 O2 would have 2 mol
you said 1 mol
and one guy from yahoo said 0.5 mol :eek:
"32 g of 1/2 O2 would be half of the moles you found of 32g O2"

Anyway 3 people so far are saying that they can't be the same.


Basically you are saying that the coefficient doesn't count even though the number in the back counts, right?

100g of 1/2O2 doesnt make any sense to me. are you trying to find moles so you can use it to find the quantity of another molecule (like in a combustion reaction or something)? you would use the coefficients in front of the molecule as a proportion, not to determine the actual mole quantity.

does the 100g of 1/2O2 make sense to everyone but me?

come to think of it....it doesn't make sense :)
and I don't know where I got these questions from.
I wrote them down from last yr and i had them unanswered at that time and I asked here but I guess the questions are wrong?

There is no such element or compund as half O2. 32g contradicts 1/2 O2, because 1/2 O2 is only 16 grams. The question is wrong.