Water can be produced from the reaction of hydrogen gas and oxygen. How many liters of hydrogen is needed to completely react with 5 liters of oxygen?

1 Answer
Simon Moore
Apr 25, 2018

Under what conditions? If you assume 25 degrees C and 1 atm the answer is just under 10 litres.

Explanation:

The reaction is #2H_2 (g) + O_2(g) -> 2H_2O(l)#

So for every mole of oxygen gas you need 2 moles of hydrogen gas. If you treat both hydrogen and oxygen as ideal gasses (which is not quite true but close enough for our purposes) you can then say that a mole of an ideal gas at 25 degrees celcius and 1 atm pressure is 24.5 litres.

So 5 litres of oxygen is (5/24.5) = 0.20 moles. You will therefore need 0.40 moles of hydrogen, which is 0.40 x 24.5 = 9.8 litres.

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