Explain why the following compounds behave as Lewis acids?

(i) BCL3 is an electron-deficient compound because it has 6 electrons in its outermost orbital and a vacant p orbital. Hence, it acts as Lewis acid and accepts a lone pair of electrons.

(ii) AlCl3 forms a covalent bond with chlorine by forming three single bonds of chlorine as aluminium has three electrons in its valence shell and act as an electron-deficient compound and act as lewis acid.

26. Give reasons for the following:

(i) CCl4 is immiscible in water, whereas SiCl4 is easily hydrolyzed.

(ii) Carbon has a strong tendency for catenation compared to silicon.

Solution:

(i) CCl4 is insoluble in water as water is polar and CCl4 is non-polar. The carbon atom has no empty orbital to accept the electrons donated by oxygen in the water. SiCl4 is easily hydrolyzed because Si has an empty d orbital to accommodate the electrons from oxygen atom of water.

(ii) The energy difference between the Carbon-Carbon and silicon-silicon bond energy is very high i.e. the tendency of carbon to form catenation is greater than the silicon.