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Chemistry 7 Online
OpenStudy (anonymous):

if 3 moles of hydrogen burn with excess oxygen, how many liters of water vapor will form?

OpenStudy (wolfe8):

First, write a balanced equation for the reaction. Next, can you find the number of moles of whatever substance you have? Use this: http://www.ptable.com/

OpenStudy (anonymous):

_3H + _O 2 -> _ H2O

OpenStudy (anonymous):

not sure how to find the moles...

OpenStudy (wolfe8):

That is not balanced. Can you balance it first?

OpenStudy (anonymous):

4 3H + 2 O2 ---> 6 H2O

OpenStudy (wolfe8):

Your oxygen is not balanced. And hydrogen does not exist as single molecules. They are always diatomic. It is H2 not H

OpenStudy (anonymous):

Opps! I totally forgot! its 2 3H2 + 3 O2 ----> 6 H2O

OpenStudy (wolfe8):

Yup looks right to me. Now, the number of moles is the mass of a substance divide by its molar mass. Can you do that?

OpenStudy (anonymous):

Which reactant or product am i finding the moles for?

OpenStudy (wolfe8):

You are only given the mass of hydrogen which is the reactant.

OpenStudy (anonymous):

i'm still confused... We given the mass of Oxygen as will in the balanced equation? If we were originally given 3 moles would that just be it...?

OpenStudy (wolfe8):

Ooh you weren't given the mass, you were given the number of moles of hydrogen. So you're looking for the volume of H2O. So from the balanced equation, you can see that portions of H2 will produce 6 portions of H2O. How would you get the number of moles of H2O then?

OpenStudy (anonymous):

would it be the overall mass converted to moles? 203.9748 * ( 1 mol / 6.002 *10^23 )

OpenStudy (wolfe8):

Duuuude. We didn't even balance the equation correctly. Ok new equation what @chmvijay said.

OpenStudy (chmvijay):

2H2+O2 ------>2H2O when two moles of H2 react with excess oxygen it produces 2 moles of water (by above formula) so for 2 moles of H2 produces 2 moles of water so 3 moles of water produces = 3 moles of water 1 mole of water= 16 g of water 3 mole of water = 16 *3 =48 g of water density = mass /volume u do and get the volume

OpenStudy (wolfe8):

Wait we aren't given the density. I think we're supposed to use STP

OpenStudy (chmvijay):

density of water is almost =1 its basic no need to mention

OpenStudy (chmvijay):

@lelenall did u get what i said above ?

OpenStudy (anonymous):

Yesss!!!! That was actually so helpful!!!! Thank you!!!! :))

OpenStudy (anonymous):

@chmvijay

OpenStudy (chmvijay):

ur welcome :)

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