What happens when ionic compounds dissolve in water?
a) They split up H2O molecules into H and O
b) They are transformed into non-metals
c) Cations and anions are released into the solution
d) They stick to the wall of the beaker
The correct answer and explanation is :
Correct Answer: c) Cations and anions are released into the solution
When ionic compounds dissolve in water, they dissociate into their constituent ions — cations (positively charged ions) and anions (negatively charged ions). This process is known as dissociation or ionization in solution.
Ionic compounds are formed through the electrostatic attraction between oppositely charged ions. For example, table salt (NaCl) consists of sodium ions (Na⁺) and chloride ions (Cl⁻). In the solid state, these ions are arranged in a rigid crystal lattice. However, when such a compound is placed in water, the polar water molecules interact with the ions.
Water is a polar solvent, meaning it has a partial positive charge near the hydrogen atoms and a partial negative charge near the oxygen atom. These polar regions surround the individual ions in the crystal lattice. The slightly negative oxygen ends of water molecules are attracted to cations, while the slightly positive hydrogen ends are attracted to anions. This weakens the ionic bonds in the crystal, pulling the ions away from the lattice and into solution.
Once separated, the ions become hydrated — they are surrounded by a shell of water molecules, which stabilizes them in the solution and prevents them from recombining. As a result, the ionic compound is said to have “dissolved,” and the solution becomes capable of conducting electricity because of the presence of free-moving charged particles.
This behavior is fundamental to many biological and chemical processes. It explains why substances like salt, when dissolved in water, create electrolytic solutions that can carry electric current.
The other options are incorrect:
- (a) Ionic compounds don’t split water molecules.
- (b) They don’t change into non-metals.
- (d) They dissolve, not stick to the beaker.