Cells that convert fuel such as hydrogen directly into electricity with water as the product.
Practise Acids, Bases & Electrochemistry All Acids, Bases & Electrochemistry topics
A fuel cell continuously converts a fuel, usually hydrogen, into electricity as long as reactants are supplied from outside. Hydrogen is oxidized at the anode and oxygen is reduced at the cathode, separated by a proton-exchange membrane that lets protons pass while forcing electrons through the external circuit. The only product of a hydrogen fuel cell is water, so the device is clean at the point of use. Fuel cells can reach efficiencies of 40 to 60 percent, which is higher than most heat engines. They are used in spacecraft and are being developed for vehicles and power stations.
Key ideas: A fuel cell continuously supplies fuel and oxidant. H2/O2 acidic (PEM): anode H2 giving 2H+ + 2e-, cathode O2 + 4H+ + 4e- giving 2H2O, E standard 1.23 V, practical 0.6 to 0.8 V. Efficiency is around 40 to 60 percent, above heat engines limited by Carnot. Types: PEM, alkaline, SOFC, MCFC, PAFC.
Common mistakes and connections: Mistakes: calling fuel cells batteries that store energy (reactants are supplied externally) and claiming zero emissions regardless of how hydrogen is produced. Catalysts such as Pt are needed. Efficiency is delta G over delta H: for H2 combustion it is 237/286, about 83 percent theoretical. Links to hydrogen production by electrolysis.
A hydrogen fuel cell burns H2 electrochemically: protons cross the membrane, electrons do work in the circuit, and the only product is water. The interactive lesson shows this as a live animation or chart.
The Apollo spacecraft used hydrogen-oxygen fuel cells to supply both electrical power and drinking water.
Cells that convert fuel such as hydrogen directly into electricity with water as the product.
Fuel Cells is a intermediate topic in Acids, Bases & Electrochemistry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Acids, Bases & Electrochemistry first: Lead-Acid Battery, Lithium-Ion Battery, Nickel-Metal Hydride Battery.
The next topics in Acids, Bases & Electrochemistry are Solid-State Batteries and Corrosion.
Yes. The interactive lesson includes a self-check question on Fuel Cells, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Fuel Cells is topic 73 of 105 in Acids, Bases & Electrochemistry.