Question

Why does salt dissolve in water?

A. The positive charges of sodium (Na) and the negative charges of chloride (Cl) interact with water molecules B. The NaCl molecules form covalent bonds with the surrounding water molecules C. The water molecules are attracted to the nonpolar bonds of the sodium and chloride ions D. The ionic bond between the sodium ion and chloride ion is strong E. None of the above

Answer 1

Answer from the above options is A PART

When we try to dissolve an ionic compound by stirring it in water, the positive poles of the water molecules are attracted to the anions, while the negative poles of other water molecules are attracted to the cations, so the polar water molecules "pull" the ions out of a crystal. As a result of these interactions, the ionic bonds eventually break and ions are released into the water. When the salt is dissolved, every ion is surrounded by water molecules, creating a kind of concentric shells of polar water molecules centered around the ions. (They also look like petals of a daisy). This process is called "hydration."

The hydration of its ions causes a salt crystal to break apart (dissolve) in the water. Therefore, when table salt (NaCl) is dissolved, two hydrated ions appear in the water: a positively cation Na+ and a negative charged anion Cl-. Each is surrounded with a shell of closely attracted water molecules that prevent the ions from reconciling into a crystal again.

These watery shells prevent the ions from getting together again into a solid. Hydrated ions jostles around the solution, dispersing evenly in the solution and causing the particles to disappear from view as they are spreading within the solution. The hydrated ions are so small that we cannot see them even with a strong microscope. and therefore we see the process as a disappearance of particles from view as the dissolving progresses.

Different ions can attract different number of water molecules into the "watery shell" because they can have different strength (density) of their charge. The density of the charge depends on the ratio of charge to surface area of an ion; the larger the ratio, the larger the hydration number will be.