Final answer:
18-crown-6 is the crown ether that solvates potassium ions due to its cavity size that matches the size of the potassium ion. Option D is correct.
Step-by-step explanation:
The crown ether that solvates potassium ions is 18-crown-6. This is because 18-crown-6, which has a chemical formula of C₁₂H₂₄O₆, has a cavity size that is well suited to accommodate the size of a potassium ion (K+), allowing it to effectively wrap around and solvate the ion.
Crown ethers like 12-crown-5 or 15-crown-5 have smaller rings and are, therefore, less suitable for the larger potassium ion relative to sodium or smaller cations. 18-crown-6 is known for its ability to complex with alkali metal ions and its affinity for potassium ions in particular.
18-crown-6 is an organic compound that can bind to group 1 metal ions, including potassium, by wrapping around them in aqueous solutions. It can fit the K+ ion better than any other crown ether due to its specific size.