If ammonia is dissolved in water, pH of the solution

Options

A. increase
B. Dereases
C. May increase or decrease
D. None of these

Answer

To determine the pH of a solution when ammonia (NH₃) is dissolved in water, we can follow these steps:

### Step 1: Understand the Dissolution of Ammonia
When ammonia gas is dissolved in water, it reacts with water to form ammonium hydroxide (NH₄OH). The reaction can be represented as:
\[ \text{NH}_3 (aq) + \text{H}_2\text{O} (l) \rightleftharpoons \text{NH}_4^+ (aq) + \text{OH}^- (aq) \]

### Step 2: Identify the Nature of the Solution
Ammonia is a weak base. When it dissolves in water, it partially ionizes to produce hydroxide ions (OH⁻). The presence of these hydroxide ions indicates that the solution is basic.

### Step 3: Determine the pH of the Solution
Since the solution is basic due to the formation of hydroxide ions, we can conclude that the pH will be greater than 7. The exact pH value will depend on the concentration of ammonia in the solution.

For a dilute solution of ammonia, the pH can typically range from about 11 to 12. To calculate the exact pH, we would need to know the concentration of the ammonia solution and use the formula:
\[ \text{pOH} = -\log[\text{OH}^-] \]
Then, we can find the pH using:
\[ \text{pH} + \text{pOH} = 14 \]

### Conclusion
In summary, when ammonia is dissolved in water, it forms a basic solution, resulting in a pH greater than 7.

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