Final answer:
IR plates should be washed with dichloromethane or another non-hydroxylic solvent to prevent water contamination and interference with analysis. Polar solvents like water are not used because they can leave residues that could disrupt measurements.
Step-by-step explanation:
Infrared (IR) plates should be washed with a non-hydroxylic solvent such as dichloromethane because it does not contain OH groups that can form hydrogen bonds with the surface of the IR plates, possibly leading to water contamination of the sample. Water is not typically used because it is a polar protic solvent and can leave behind residues that would interfere with analysis. Non-polar solvents, like carbon tetrachloride (CCl4) mentioned in some examples, are preferred because they can efficiently clean the plate without leaving behind interfering residues. The solubility of substances often depends on the polarity of both the solvent and the solute. For instance, polar substances like methanol (CH3OH) and sodium sulfate (Na2SO4) are soluble in polar solvents like water, while nonpolar substances such as octane (C8H18) and iodine (I2) are more soluble in nonpolar solvents such as CCl4.