<P> The number of hydrogen molecules produced is thus twice the number of oxygen molecules . Assuming equal temperature and pressure for both gases, the produced hydrogen gas has therefore twice the volume of the produced oxygen gas . The number of electrons pushed through the water is twice the number of generated hydrogen molecules and four times the number of generated oxygen molecules . </P> <P> Decomposition of pure water into hydrogen and oxygen at standard temperature and pressure is not favorable in thermodynamic terms . </P> <Table> <Tr> <Td> Anode (oxidation): </Td> <Td> 2 H O (l) </Td> <Td> → </Td> <Td> O (g) + 4 H (aq) + 4e </Td> <Td> </Td> <Td> E = + 1.23 V </Td> </Tr> <Tr> <Td> Cathode (reduction): </Td> <Td> 2 H (aq) + 2e </Td> <Td> → </Td> <Td> H (g) </Td> <Td> </Td> <Td> E = 0.00 V </Td> </Tr> </Table> <Tr> <Td> Anode (oxidation): </Td> <Td> 2 H O (l) </Td> <Td> → </Td> <Td> O (g) + 4 H (aq) + 4e </Td> <Td> </Td> <Td> E = + 1.23 V </Td> </Tr>

What is observed when electrolysis of water is done