Energy Changes: Chemical Cells and Fuel Cells

Understanding Chemical Cells

A chemical cell generates electrical energy from a spontaneous chemical reaction.
The cell consists of two different metals (the electrodes) submerged in a solution that can conduct electricity (an electrolyte).
The metals react with the electrolyte, which leads to a build-up of electrons on one of the metal electrodes. This excess creates a voltage, and when a wire connects the two metals (forming a complete circuit), electricity flows.
Voltage or potential difference of a chemical cell depends on the type of electrodes and electrolyte employed.

Understanding Fuel Cells

Fuel cells also convert chemical energy into electricity, but instead of having a fixed supply of chemicals inside the cell, they use external supplies of fuel and oxygen (or air).
Hydrogen is a commonly used fuel which reacts with oxygen to form water, generating electricity in the process.
The main advantage of fuel cells over conventional chemical cells is that they don’t run out as long as fuel is supplied, making them ideal for powering vehicles or supplying power in remote locations.

Energy Changes in Chemical Cells and Fuel Cells

The reactions in both chemical and fuel cells are exothermic. The energy is released when the new bonds in the products form is greater than the energy needed to break the bonds in the reactants.
For both cell types, the ΔH is negative, indicating that energy is released.

Practical Applications of Chemical Cells and Fuel Cells

Chemical cells can be used to power small, portable devices like torches, radios, or remote controls.
Hydrogen fuel cells are a promising technology for electric cars, as they produce no pollutants, only water vapour, and they can run as long as hydrogen fuel is supplied.

Challenges with Chemical Cells and Fuel Cells

Both types of cells must carefully control the reactions to avoid dangerous situations. For example, hydrogen is highly flammable and must be handled with care in a fuel cell.
Disposing of spent chemical cells can result in environmental contamination if not done properly.
Hydrogen gas is not readily available in large quantities and producing it can be expensive and environmentally impactful.
Fuel cells are also less efficient at lower temperatures compared to higher temperatures.

How to Improve Energy Output in Chemical Cells

The cell’s energy output can be improved by changing the materials used for the electrodes or the electrolyte.
Alternatively, a more potent fuel or a better catalyst can be used in a fuel cell to increase its energy output.