Final answer:
A protic solvent is a solvent with a hydrogen atom capable of forming hydrogen bonds due to being bound to an electronegative atom. They are good at dissolving ionic compounds by forming a solvation layer, but are not suitable for SN2 reactions. Examples include water and methanol.
Step-by-step explanation:
A protic solvent is a type of solvent that has a hydrogen atom attached to an electronegative atom, such as oxygen or nitrogen, which can participate in hydrogen bonding. These solvents have an acidic hydrogen and can donate a proton (H+) to a reaction. Examples include water (H2O) and methanol (CH3OH). Protic solvents are capable of dissolving ionic compounds, like NaCl, through ion-dipole interactions and are known to form a solvation layer around both cations and anions.
Polar protic solvents are not suitable for SN2 reactions because the solvation layer around the anion hinders nucleophiles from effectively approaching the electrophilic center, often a carbon atom. Meanwhile, polar aprotic solvents do not have this disadvantage because they can dissolve ionic compounds but do not form a solvation layer that is as inhibiting, thereby leaving the anion more free to act as a nucleophile. This is critical for faster and more efficient SN2 reactions.
In the context of acids, a monoprotic acid is an acid that has only one ionizable hydrogen atom, such as hydrochloric acid (HCl), whereas polyprotic acids, like sulfuric acid (H2SO4), have multiple ionizable hydrogen atoms.