How Much Hydrogen Gas Is Released From Water?

Hydrogen can be produced by splitting water through a process called electrolysis.

Hydrogen used in industry is typically produced from methane (better known as natural gas). However, it also can be produced by splitting water through a process called electrolysis. The amount of hydrogen produced depends on the amount of water used.

Features

Electrolysis uses electric energy to split up water molecules; the products of this reaction are oxygen molecules (O2) and hydrogen molecules (H2). The amount of energy it takes is always greater than or equal to the energy you get from burning the hydrogen.

Size

Chemists often describe quantities of substances using a unit called the mole. One mole is 6.022 x 10 to the 23rd atoms or molecules. Since each water molecule contains two hydrogen atoms, splitting one mole of water molecules (0.634 oz) will produce one mole of hydrogen gas (H2) molecules (0.07 oz). The volume of the hydrogen gas produced will vary, because the volume of a gas varies with pressure and temperature.

Considerations

The efficiency of electrolysis (the amount of energy needed to split a given number of water molecules) may vary widely depending on the technique. Scientists are currently researching ways to produce hydrogen more efficiently, although it's important to note that the process will always consume at least as much energy as is released by burning the hydrogen gas--a consequence of the laws of thermodynamics.

References

• "Chemical Principles, the Quest for Insight, 4th Edition"; Peter Atkins and Loretta Jones; 2008
• Georgia State University HyperPhysics: Electrolysis of Water