Eli5: How is hydrogen, a potent source of fuel with high energy release, combined with oxygen, a facilitator for combustion and energy release, mix together to make water which we drink like it’s no big deal?

Question

bonus points if you can explain why water has no caloric value, but hydrogen can power huge machinery.

In: 3

Answer 1

The energy released when hydrogen and oxygen come together is the energy from forming that bond to create water molecules. These two molecules are expending their energy to combine. To split water back up you need to do the opposite, you need to provide energy to split the bond. That’s why water is the lower energy state, the energy has already been expended to make it.