The question of whether water can be created in a laboratory setting has a straightforward answer: yes, it is chemically possible. Water, or H2O, is a simple compound formed by combining hydrogen and oxygen, its two constituent elements. However, the practical application of this synthesis is highly limited. While scientists can technically synthesize water, the process is neither efficient nor economical for any purpose beyond small-scale chemical demonstrations. The creation of water does not offer a viable solution for addressing global water scarcity or supplementing municipal supplies.
Synthesizing Water from Hydrogen and Oxygen
The fundamental chemical reaction required to produce water involves mixing two molecules of hydrogen gas (H2) with one molecule of oxygen gas (O2) to yield two molecules of water (H2O). This synthesis is represented by the balanced equation: 2H2(g) + O2(g) -> 2H2O(g). Simply combining the two gases at room temperature will not result in a reaction because the strong covalent bonds holding the H2 and O2 molecules together must first be broken.
The reaction requires an initial input of energy, known as activation energy, to destabilize the reactant molecules. This energy can be provided by a spark, a flame, or an electrical current in a controlled environment. Once initiated, the reaction is highly exothermic, meaning it releases a significant amount of heat energy as the new chemical bonds of water are formed.
This rapid energy release can be vigorous, often resulting in an explosion if the gases are mixed in high concentrations. In a safe laboratory setting, the reaction is controlled in specialized chambers. It is also used in applications like hydrogen fuel cells, which use catalysts to manage the reaction and convert chemical energy directly into electricity. The water produced is initially hot steam or water vapor due to the heat generated.
The Energetic and Economic Limitations of Creation
The chemical synthesis of water is not a practical method for large-scale production due to high energetic and economic costs. The massive energy requirement stems not from the synthesis reaction itself, but from obtaining the pure elemental gases, hydrogen and oxygen. Hydrogen is often sourced by splitting water in a process called electrolysis, which requires a substantial energy input.
It takes more energy to isolate the hydrogen and oxygen for synthesis than the energy released when they combine, resulting in a net energy loss. Seawater desalination, a common method for creating fresh water, consumes about 3 to 4 kilowatt-hours of electricity for every cubic meter. The energy required to generate the hydrogen needed to synthesize that same volume of water is exponentially higher, making the process fiscally non-viable.
The infrastructure required to handle the volatile reactant gases safely is extensive and costly. Storing and managing large quantities of pressurized hydrogen gas presents significant safety hazards, including the risk of explosion. The costs associated with energy consumption, specialized equipment, and safety protocols far outweigh the expense of alternative methods like purification or desalination.
How Scientists Obtain Ultra Pure Water
In a laboratory setting, scientists prefer to purify existing water sources rather than synthesizing water. Scientific experiments require different grades of purity, classified based on the level of dissolved ions, organic compounds, and microorganisms they contain. For highly sensitive procedures, ultra-pure water is required, which is defined by its high electrical resistivity, often 18.2 MΩ·cm.
The purification process involves a multi-step sequence that begins with pre-treatment to remove large particles. The most common methods include:
- Reverse osmosis (RO), where water is forced through a semi-permeable membrane to filter out salts and large contaminants.
- Deionization (DI), which uses ion exchange resins to remove remaining charged particles, or ions, from the water.
For the highest grade of purity, a final step often involves electrodeionization (EDI) or distillation.
These purification techniques are significantly cheaper, safer, and more energy-efficient than synthesizing water from scratch. This practical approach ensures that laboratories have a reliable and cost-effective supply of water that meets the exact purity specifications.