Give an example of a solid solution in which the solute is a gas.

A solid solution is a homogeneous mixture where one substance (solute) is uniformly dispersed in another solid (solvent). When the solute is a gas and the solvent is a solid, we get a gas-in-solid solution.

Example:Hydrogen in palladium (Pd-H system)

• Palladium metal can absorb large amounts of hydrogen gas, with the hydrogen atoms occupying interstitial spaces in the palladium’s crystal lattice.
• This is called an interstitial solid solution because the gas atoms fit into the gaps between the solvent’s atoms without displacing them.

Applications:

• Hydrogen storage: Palladium is used in fuel cell technology for storing and releasing hydrogen efficiently.
• Catalysis: The absorbed hydrogen participates in catalytic hydrogenation reactions in organic chemistry.

Why it forms:

The atomic radius of hydrogen is small enough to fit into the metallic lattice voids of palladium without significantly distorting the crystal structure. This allows the hydrogen atoms to move freely within the lattice while remaining uniformly distributed.