page 30 Flashcards
What types of ions do polar protic solvents solvate?
A: Both cations and anions.
How are Na⁺ cations solvated in water?
A: By ion-dipole interactions with H₂O molecules.
What interactions solvate Br⁻ anions in water?
A: Strong hydrogen bonding interactions.
What is an ion-dipole interaction?
A: An attraction between an ion and the partial charges on a polar molecule.
Why is NaBr a good example for studying solvation by polar protic solvents?
A: It dissociates into Na⁺ and Br⁻ ions, both of which are solvated differently by water.
In solvation of Na⁺, which part of the water molecule interacts with the ion?
A: The oxygen atom (δ⁻) of the water molecule.
What is the role of hydrogen bonding in the solvation of anions?
A: It stabilizes the anion by surrounding it with partial positive charges from hydrogen atoms in water.
What is the partial charge on oxygen in a water molecule?
A: Partial negative (δ⁻).
What is the partial charge on hydrogen in a water molecule?
A: Partial positive (δ⁺).
How does the solvation of cations differ from that of anions?
A: Cations are solvated by the negative dipole of oxygen, while anions are solvated by the positive dipole of hydrogen.
Why are polar protic solvents effective in nucleophilic substitution reactions?
A: They stabilize the ions formed during the reaction through solvation.
What happens to the nucleophile’s reactivity in polar protic solvents?
A: The reactivity may decrease due to strong hydrogen bonding with the solvent.
What type of solvation occurs for Br⁻ in water?
A: Hydrogen bonding with water molecules.
How does solvation affect the rate of substitution reactions?
A: Solvation stabilizes intermediates, which can increase or decrease the reaction rate depending on the mechanism.
