Question

Some of the following salts are used in detergents and other cleaning materials because they produce basic solutions. Which of the following could not be used for this purpose? Write equations to justify your answers.

a. Sodium carbonate
b. Sodium sulfate
c. Ammonium sulfate
d. Sodium phosphate

Answer 1

Answer: Sodium sulfate and Ammonium sulfate could not be used for this purpose.

Explanation:

An acidic solution will show a pH in the range of 0 - 6.9. A basic solution show a pH in the range of 7.1 - 14. A neutral solution will show a pH of 7.

A salt is acidic, when it is formed from the combination of strong acid and weak base. A salt is basic, when it is formed from the combination of weak acid and strong base. A salt is neutral, when it is formed from the combination of weak acid and weak base or strong acid and strong base.

a. Sodium carbonate : is formed by the combination of strong base $NaOH$ and a weak acid $H_2CO_3[$, thus forms a basic solution.

$Na_2CO_3\rightarrow 2Na^++CO_3^{2-}$

b. Sodium sulfate:  is formed by the combination of strong base $NaOH$ and a strong acid $H_2SO_4[$, thus forms a neutral solution.

$Na_2SO_4\rightarrow 2Na^++SO_4^{2-}$

c. Ammonium sulfate:  is formed by the combination of weak base $NH_4OH$ and a strong acid $H_2SO_4[$, thus forms a acidic solution.

$(NH_4)_2SO_4\rightarrow 2NH_4^++SO_4^{2-}$

d. Sodium phosphate:  is formed by the combination of strong base $NaOH$ and a weak acid $H_3PO_4[$, thus forms a basic solution.

$Na_3PO_4\rightarrow 3Na^++PO_4^{3-}$