Question

Which of the following salts will give highest $ pH $ in water?

• A. $KCl$
• B. $NaCl$
• C. $ Na_2CO_3 $
• D. $ CuSO_4 $

Answer 1

The Correct Option is C

To determine which salt will give the highest pH in water, we need to understand the nature of hydrolysis of salts when dissolved in water.

Let's analyze each option:

1. KCl: This is a salt formed from a strong acid (HCl) and a strong base (KOH). It does not hydrolyze in water and the solution remains neutral, with pH \approx 7.
2. NaCl: Similar to KCl, NaCl is also formed from the neutralization of a strong acid (HCl) with a strong base (NaOH). Thus, its solution in water is neutral, with pH \approx 7.
3. Na_2CO_3: This salt is formed from a weak acid (H₂CO₃) and a strong base (NaOH). When dissolved in water, it hydrolyzes to form carbonate ions which increase the concentration of hydroxide ions in the solution, making it basic. Therefore, the pH will be greater than 7.
4. CuSO_4: This is a salt derived from a strong acid (H₂SO₄) and a weak base (Cu(OH)₂). It hydrolyzes to produce an acidic solution, lowering the pH.

Thus, among the given options, Na_2CO_3 will give the highest pH when dissolved in water because it forms a basic solution due to the hydrolysis of carbonate ions.

The correct answer is Na_2CO_3.