1. Hydrolysis of Carbonate Ions:
* When sodium carbonate dissolves in water, it dissociates into sodium ions (Na⁺) and carbonate ions (CO₃²⁻).
* Carbonate ions react with water molecules in a process called hydrolysis, forming bicarbonate ions (HCO₃⁻) and hydroxide ions (OH⁻):
```
CO₃²⁻(aq) + H₂O(l) ⇌ HCO₃⁻(aq) + OH⁻(aq)
```
* The presence of hydroxide ions (OH⁻) in the solution makes it alkaline.
2. Weak Acid and Strong Base Salt:
* Sodium carbonate is formed from the reaction of a strong base (sodium hydroxide, NaOH) and a weak acid (carbonic acid, H₂CO₃).
* Salts formed from strong bases and weak acids tend to be alkaline in nature.
3. pH Value:
* The pH of a sodium carbonate solution is greater than 7, indicating its alkaline nature.
In summary:
The hydrolysis of carbonate ions in water produces hydroxide ions, which are responsible for the alkaline nature of sodium carbonate solution. The presence of hydroxide ions leads to a higher pH value than 7, confirming its alkalinity.
