Gen Chem simple set up problem

[IdahoDoc]

If someone could please explain how they are setting up this problem that would be great. I can do the math out and get the correct answer i just don't see how they set it up. thanks

 

[Svart Aske]

It doesn't display on my Word. You might want to repost in another format if others can't see.

 

[yankees27th]

Same here. Word pops up and says "quicktime and decompressor are needed to see this picture"

 

[IdahoDoc]

Thanks guys I will try to do it another way.

 

[Panther85]

Qhow many moles of water are formed from 100g H2 and 100g O2 asssuming the reaction goes to completion?

1) write out formula: H2+.5O2-> H2O
2) find limiting reactant- its oxygen bc it has a heavier molar mass compared to hydrogen therefore there are less moles of O2 in 100g than moles of H2. dont bother doing the calculation: save time
3) set up dimensional anaylsis:
)
100 g O2 x (1 mol O2/ 32g O2) x ( 1 mol H2O/ .5 mol O2) = 100/(32x.5) or 2(100/32) which is choice C

 

[IdahoDoc]

http://i549.photobucket.com/albums/ii373/idahodoc/Untitled1.jpg

 

[IdahoDoc]

Qhow many moles of water are formed from 100g H2 and 100g O2 asssuming the reaction goes to completion?

1) write out formula: H2+.5O2-> H2O
2) find limiting reactant- its oxygen bc it has a heavier molar mass compared to hydrogen therefore there are less moles of O2 in 100g than moles of H2. dont bother doing the calculation: save time
3) set up dimensional anaylsis:
)
100 g O2 x (1 mol O2/ 32g O2) x ( 1 mol H2O/ .5 mol O2) = 100/(32x.5) or 2(100/32) which is choice C

Thanks Panther 85, I got it now I was skipping this part (1 mol H2O/ .5 mol O2).