Electrolysis and energy

  • Thread starter Patrickas
  • Start date
  • #1
20
0

Main Question or Discussion Point

How much electric energy needs to be used, to get 2.5l of hydrogen, when T=298K, pressure 10^5Pa? Electrolysis happens at 5V, efficiency is 75%.

I am quite lost here. Not sure were to start. I tried finding the needed current by getting hydrogen to kg and then by comparing to 0.0104*10^-6kg/C (electrolysis). I get 21.6*10^3C.
Energy - E=21600*5*0.75=60.75*10^3J

Of course wrong.

Second try:
n(H)=PV/RT i get that hydrogen has 0.1mole=0.1g=100C to electrolyse it.
Then E=100*5*0.75=375J - WRONG
 
Last edited:

Answers and Replies

  • #2
2,544
2
maybe look at the Bond dissociation energy , or the coulomb energy ,
E= q1*q2/(4pi*e*r)
q1 and q2 are the charges , e=permitivity constant r is the radius between the charges .
 
  • #3
20
0
maybe look at the Bond dissociation energy , or the coulomb energy ,
E= q1*q2/(4pi*e*r)
q1 and q2 are the charges , e=permitivity constant r is the radius between the charges .
Very much doubt it... but if you got an answer...
 
  • #4
2,544
2
you are trying eltrolzoye water or hydrogen .
 
  • #5
20
0
you are trying eltrolzoye water or hydrogen .
It doesn't say.
 
  • #6
2,544
2
well this might be the wrong way to go about this but it take
4.52eV electron volts , to break the H2 bond.
 
  • #7
20
0
O maybe the answer to the problem will help - 0.13MJ
 
  • #8
20
0
nothing?....damnnnnnn
 
  • #9
2,544
2
ya man i would like to help but I’m at a loss , I don’t know why other people haven’t jumped in yet .
 
  • #10
20
0
If anyone is interested how to solve it read along. :smile:

"You have 0.1 mole of hydrogen gas produced (from pV=nRT)
So far so good
Multiply by Avogadro's number to find number of hydrogen molecules
Each molecule needs 2 hydrogen atoms
Each atom had a charge = 1.6 x 10^-19 C
Multiply number of atoms by this to get total charge
Energy transfer = voltage times charge, E=VQ
With only 75% efficiency the energy actually needed is this value divided by 0.75
Plug in the numbers and you get the quoted answer."

This is a quote from the solver.
 

Related Threads for: Electrolysis and energy

Replies
13
Views
1K
  • Last Post
Replies
3
Views
1K
Replies
2
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
8
Views
4K
  • Last Post
Replies
2
Views
5K
Replies
10
Views
835
  • Last Post
Replies
1
Views
1K
Top