No, sulphuric acid and sodium cyanide cannot both be used to prevent hydrolysis - in fact, they have opposite effects.
1. Role of sulphuric acid (H₂SO₄):
- Sulphuric acid is a strong acid.
- It increases the concentration of H⁺ ions in the solution.
- This suppresses hydrolysis by shifting the equilibrium backward (Le Chatelier’s Principle).
Conclusion: Sulphuric acid prevents hydrolysis.
2. Role of sodium cyanide (NaCN):
- Sodium cyanide is a salt of a strong base (NaOH) and weak acid (HCN).
- In water, it produces CN⁻ ions, which undergo hydrolysis:
CN⁻ + H₂O ⇌ HCN + OH⁻
- This releases OH⁻ ions, making the solution basic.
Conclusion: Sodium cyanide promotes hydrolysis, not prevents it.
Important Safety Note:
Mixing sodium cyanide with acids (like H₂SO₄) is extremely dangerous, as it produces hydrogen cyanide (HCN) gas, which is highly toxic.
Key Takeaway:
- Sulphuric acid prevents hydrolysis by increasing acidity.
- Sodium cyanide promotes hydrolysis by making the solution basic and should never be mixed with acids.