Acetone major species present when dissolved in water
The correct answer and explanation is:
When acetone (CH₃COCH₃) is dissolved in water, the major species present are acetone molecules, water molecules, and some small amount of acetone ions. Acetone is a highly polar molecule, but it does not ionize significantly in water. Therefore, the primary species are acetone molecules and water molecules.
Acetone is an organic solvent, and when it is mixed with water, it interacts with the water molecules through hydrogen bonding. The carbonyl group (C=O) in acetone is polar, and the oxygen atom can form hydrogen bonds with the hydrogen atoms of water molecules. As a result, acetone is soluble in water, as the hydrogen bonding between acetone and water molecules lowers the energy required for the two substances to mix.
The solubility of acetone in water is relatively high because of the hydrogen bonding between the acetone and water molecules. This is a case of miscibility, where two liquids can mix in any proportion. Unlike nonpolar compounds, which do not interact well with water molecules, acetone’s polar carbonyl group allows it to mix readily with water.
While acetone does not dissociate into ions in water, a very small amount of ionization might occur under certain conditions, where the water molecules could slightly break apart acetone into protonated and deprotonated forms. However, this ionization is negligible compared to the number of acetone molecules and water molecules in solution.
Therefore, the major species present in the solution are acetone molecules, water molecules, and negligible quantities of acetone ions. The solution remains primarily molecular without significant ion formation.