Question

In the combustion of hydrogen gas, hydrogen reacts with oxygen from the air to form water vapor.
Hydrogen+Oxygen->Water
If you burn 39.7 g of hydrogen and produce 355g of water, how much oxygen reacted?

Answer 1

I started my problem by writing a balanced equation of the reaction but now I haven't the slightest idea of what to do with it. 2H2+O2->2H20

Answer 2

How many moles are in 39.7 g of Hydrogen? How many moles of hydrogen are in 355 g of water? How many moles of water are in 355 g of water?

We need these three values to determine if the combustion process is stoichiometric.

Answer 3

How would I figure the moles H/355g H20?

Answer 4

isn't simply a matter of 355 - 39.7 g oxygen

Answer 5

355 g of water = 355/18 moles

Answer 6

Did you figure out the number of moles of hydrogen and water?

Answer 7

Hydrogen+Oxygen->Water If you burn 39.7 g of hydrogen and produce 355g of water, how much oxygen reacted?

so you have 355 grams of water in the end or the process

Find the g/mol of H2O

355g H2O *(Oxygen g/mol/H2O g/mol) = grams of oxygen you reacted

Answer 8

To find the g/mol of H2O simply (hydrogen g/mol)*2 + (g/mol of oxygen) = H2O g/mol

Answer 9

355g H2O *(15.9994 g/mol/18.0153 g/mol) = 315.28 grams

Answer 10

of Oxygen were reacted theoretically of course assuming all the oxygen was pushed forward to water.

Answer 11

if you look at the formula you will notice the g/mol cross out and the H2O and the H2O cross out so all you are left with is Oxygen and grams

Answer 12

Hope this helps

Answer 13

355 - 39.7 = 315.3 g

Answer 14

jimmy rep your answer is just as good as mine but what i have provided her is much more universal for dealing with problems like this that are a little more complex but yeah.

Answer 15

It's helping but I'm getting confused.
I know that there's 39.7mol H per 39.7g H
You said to do 39.7g*2=79.4
79.4+(g/mol of oxygen) = H2O g/mol
Now I'm just guessing 79.4+16=95.4
Sorry guys it's been a few years since I've done chemistry

Answer 16

yea - i agree

Answer 17

from equation and using approximate moles of reactants

2 H2 = 4 (4*1)
02 = 32 (2*16)
2 H20 = 36 (4+32)
ratio 1:8:9
39.7 g of hydrogen reacts with 8*39.7 g oxygen giving 9* 39.7 g water

Answer 18

Okay, now I get it.
At first I solved it the same as Jimmy because of the Law of Conservation of Mass
but I figured I should learn the proper way.

Thank you to all who helped!!

Answer 19

yw