Question

The compound whose aqueous solution has the highest $P^H$ is

• A. NaCl
• B. $NaHCO_3$
• C. $Na_2CO_3$
• D. $NH_4Cl$

Answer 1

The Correct Option is C

To determine which compound's aqueous solution has the highest P^H, we need to understand the nature of the compounds when dissolved in water:

1. NaCl (Sodium Chloride): When dissolved in water, sodium chloride dissociates into Na⁺ and Cl^- ions. These ions are neutral and do not affect the PH of the solution significantly, resulting in a neutral solution with a PH around 7.
2. NaHCO_3 (Sodium Bicarbonate): Sodium bicarbonate is a basic salt which can dissociate into Na⁺ and HCO₃^- ions. The bicarbonate ion (HCO₃^-) can further react with water to produce OH^- ions, which increases the PH above 7, making it a basic solution.
3. Na_2CO_3 (Sodium Carbonate): Sodium carbonate dissociates into 2Na⁺ and CO₃^2- ions. The carbonate ion (CO₃^2-) is a strong base that reacts with water to produce a higher concentration of OH^- ions, significantly increasing the PH of the solution. Therefore, a sodium carbonate solution is more basic than sodium bicarbonate, resulting in a PH usually above 11.
4. NH_4Cl (Ammonium Chloride): Ammonium chloride is an acidic salt formed from a strong acid (HCl) and a weak base (NH₃). It dissociates into NH₄⁺ and Cl^- ions. The ammonium ion can donate a proton to water, forming NH₃ and H₃O⁺, which results in a decrease in PH (more acidic).

Among the given options, Na_2CO_3 is the compound whose solution has the highest PH as it produces the most OH^- ions among the compounds mentioned. Therefore, the correct answer is Na_2CO_3.