Chapter 18, Problem 3RAT

Solution

To determine: The correct option for the statement “Which would you expect to have a higher melting point: sodium chloride, NaCl, or aluminum oxide, ${\text{Al}}_2{\text{O}}_3$? ”.

Answer:

The correct option for the statement “Which would you expect to have a higher melting point: sodium chloride, NaCl, or aluminum oxide, ${\text{Al}}_2{\text{O}}_3$ ?” is option (c).

Explanation:

Atom is basically neutral and possesses zero net charges. When there exists net charge on any atom, it is considered as an ion.

The ions containing opposite charges basically attract each other and generate the ionic bond. Ionic bonding occurs when electrons get transferred.

In NaCl, chlorine and sodium ions are present. In which the sodium contains $+1$ charge whereas chlorine contains $-1$ charge.

In ${\text{Al}}_2{\text{O}}_3$, aluminum and oxide ions are present. The aluminum ion contains $+3$ charge and the three oxide ions contain $-2$ charge on each.

As the ions in ${\text{Al}}_2{\text{O}}_3$ have greater charges, the attraction among them will be stronger compared to . If attraction forces that exist are stronger then large quantity of energy is needed to dissociate the existing bonds. And thus the melting point will be higher.

Thus, ${\text{Al}}_2{\text{O}}_3$ will possess higher melting point.

Conclusion:

Therefore, the correct option for the statement “Which would you expect to have a higher melting point: sodium chloride, NaCl, or aluminum oxide, ${\text{Al}}_2{\text{O}}_3$?” is option (c).