Question

The melting point of ${\mathbf{TiCl}}_{\mathbf{4}}$$\left(\mathbf{-}\mathbf{24}\mathbf{°}\mathbf{C}\right)$lies below those of ${\mathbf{TiF}}_{\mathbf{4}}$$\left(\mathbf{284}\mathbf{°}\mathbf{C}\right)$and ${\mathbf{TiBr}}_{\mathbf{4}}$$\left(38°C\right)$. Explain why by considering the covalent-ionic nature of these compounds and the intermolecular forces in each case.

Short answer

The melting point of${\text{TiCl}}_{\text{4}}$ is $-24°\text{C}$is because it is a covalent network solid. On the other hand, the weaker forces in${\text{TiBr}}_{\text{4}}$ than ${\text{TiF}}_{\text{4}}$, makes it have a low melting point.

Step-by-step solution

Intermolecular forces

Intermolecular forces indicate the type of interaction within the atoms or molecules. The intermolecular forces' magnitude affects a particular molecule's boiling point.

Ionic and covalent compounds

Ionic compounds are created by the electron transfer from the cation to the anion. Covalent compounds are created by electron sharing among the atoms. These compounds have lesser melting points as they have weaker forces than ionic ones.

The difference in melting points of the different compounds

The melting point ${\text{TiF}}_{\text{4}}$of is $284°\text{C}$and ${\text{TiBr}}_{\text{4}}$is ${38}^{\circ }\mathrm{C}$ . The melting point of ${\text{TiCl}}_{\text{4}}$is $-24°\text{C}$which is less than both the compounds. It is because it is a covalent network solid. Different tetrahedral units of${\text{TiCl}}_{\text{4}}$ are connected together by weaker intermolecular forces. Hence, it has fewer melting points. On the other hand, the weaker forces in ${\mathbf{TiBr}}_{\mathbf{4}}$than ${\mathbf{TiF}}_{\mathbf{4}}$, makes it have a low melting point.