With fossil fuels becoming more expensive and less available, scientists are looking for other energy sources. Hydrogen has long been considered an ideal source, since it does not pollute when it burns. The problem has been finding ways to generate hydrogen economically. One new approach that is being studied is photoelectrolysis – the generation of electricity using photovoltaic cells to split water molecules. This technique is still in the research stage, but appears to be a very promising source of power in the future.
Electrolysis of Water
The electrolysis of water produces hydrogen and oxygen gases. The electrolytic cell consists of a pair of platinum electrodes immersed in water to which a small amount of an electrolyte such as H2SO4 has been added. The electrolyte is necessary because pure water will not carry enough charge due to the lack of ions. At the anode, water is oxidized to oxygen gas and hydrogen ions. At the cathode, water is reduced to hydrogen gas and hydroxide ions.
In order to obtain the overall reaction, the reduction half-reaction was multiplied by two to equalize the electrons. The hydrogen ion and hydroxide ions produced in each reaction combine to form water. The H2SO4 is not consumed in the reaction.
- What are the electrodes used in the reaction?
- Why is sulfuric acid used?
- At which electrode does oxygen appear?
Use the resource below to answer the questions that follow.
- What are the electrodes?
- What is the power source?
- What is put in the water to facilitate flow of electricity?
- Which test tube contains hydrogen gas?