Question

How does adding Na2CO3 affect the hydrolysis of AlCl3?

Answer 1

How does adding Na2CO3 affect the hydrolysis of AlCl3?

Answer:

If we add $\mathrm{Na_2CO_3}$ to the solution of $\mathrm{AlCl_3}$, we will obtain $\mathrm{Al_2(CO_3)_3}$:

$$3 \mathrm{Na_2CO_3} + 2 \mathrm{AlCl_3} = \mathrm{Al_2(CO_3)_3} + 6 \mathrm{NaCl}.$$

$\mathrm{Al_2(CO_3)_3}$ has been formed by weak base $\mathrm{Al(OH)_3}$ and weak acid $\mathrm{H_2CO_3}$, therefore, this salt hydrolyzes faster than $\mathrm{AlCl_3}$:

$$\begin{array}{l} \mathrm{Al_2(CO_3)_3} + 6 \mathrm{H_2O} = 2 \mathrm{Al(OH)_3} \downarrow + 3 \mathrm{H_2O} + 3 \mathrm{CO_2} \uparrow \\ 2 \mathrm{Al^{3+}} + 3 \mathrm{CO_3^{2-}} + 6 \mathrm{H_2O} = 2 \mathrm{Al(OH)_3} + 3 \mathrm{H_2O} + 3 \mathrm{CO_2}. \end{array}$$