# Gen Chem simple set up problem

#### IdahoDoc

10+ Year Member
7+ Year Member
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

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

#### yankees27th

10+ Year Member
7+ Year Member
Same here. Word pops up and says "quicktime and decompressor are needed to see this picture"

#### IdahoDoc

10+ Year Member
7+ Year Member
Thanks guys I will try to do it another way.

#### Panther85

10+ Year Member
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

10+ Year Member
7+ Year Member

#### IdahoDoc

10+ Year Member
7+ Year Member
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).