Calculate the amount of `NH_(4)C1` required to dissolve in `500mL` of water to have a `pH = 4.5, K_(b) = 2.0 xx 10^(-5)`.

Explanation

To solve the problem of calculating the amount of ammonium chloride (NH₄Cl) required to dissolve in 500 mL of water to achieve a pH of 4.5, we can follow these steps:

### Step 1: Understand the relationship between pH, pK_w, and pK_b
We know that the pH of a solution can be related to the pK_w, pK_b, and the concentration of the solution (C) using the formula:
\[ \text{pH} = \frac{1}{2} \left( \text{pK}_w - \text{pK}_b - \log C \right) \]

### Step 2: Calculate pK_b from K_b
Given \( K_b = 2.0 \times 10^{-5} \), we can calculate pK_b:
...