Question

What volume of oxygen is produced at STP when `6.58 times 10^24` molecules of water is decomposed?

Answer 1

Every two molecules of water make for one molecule of oxygen.

Explanation:

`2H_2O->2H_2+O_2`

So there will be `0.5xx6.58xx10^24=3.29xx10^24` `O_2` molecules.

`1mol=6.02xx10^23` particles, so the amount produced is:

`(3.29xx10^24)/(6.02xx10^23)=5.47mol`

At an STP of `273K,1atm` the volume is `22.4L//mol`
(you can look up molar volumes for any other STP, there are lots of STP's)

So the volume of oxygen is `5.47xx22.4=122L`