Explore BrainMass
Share

Explore BrainMass

    Energy from Hydrogen

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    Calculate the minimum energy required to produce molecular hydrogen from gas-phase water. Then compare this to the energy need to produce water electrochemically or photoelectrochemically. Finally, compare this to the energy needed to make this on a zirconia surface. Comment on why there are differences.

    © BrainMass Inc. brainmass.com October 10, 2019, 5:36 am ad1c9bdddf
    https://brainmass.com/chemistry/oxidation-reduction-and-electrochemistry/energy-from-hydrogen-511315

    Solution Preview

    a. 2H2O (g) --> 2H2 (g) + O2 (g)

    To calculate energy required, we can use the standard enthalpy of formation for each compound in the gas phase and determine enthalpy of reaction. If it's endothermic, then this amount would be the energy required to form the gases from water vapor.

    dHreaction = [2 x dHf(H2) + dHf(O2) ] - [ 2 x dHf(H2O) ] = (0 + 0) - (-483.64 kJ)

    dHreaction = 483.64 kJ

    This is for production of 2 mol of H2.

    b. To produce H2 electrochemically, we consider the electrolysis of H2O. The reaction is the same as written above except we have water instead of water vapor. Then we use standard reduction potentials ...

    Solution Summary

    Energy from hydrogen is examined. The expert calculates the minimum energy required to produce molecular hydrogen from gas-phase water.

    $2.19