A buffer solution with pH 9 is to be prepared by mixing `NH_(4) Cl and NH_(4)OH`. Calculate the number of moles of `NH_(4)Cl` that should be added to one litre of 1.0 M `NH_(4)OH (K_(b)=1.8xx10^(-5))`

Explanation

To solve the problem of preparing a buffer solution with pH 9 by mixing \( \text{NH}_4\text{Cl} \) and \( \text{NH}_4\text{OH} \), we will follow these steps:

### Step 1: Understand the Buffer System
A buffer solution consists of a weak base and its conjugate acid. In this case, \( \text{NH}_4\text{OH} \) is the weak base, and \( \text{NH}_4\text{Cl} \) is the conjugate acid.

### Step 2: Calculate \( \text{pOH} \)
Since we know the pH of the buffer solution is 9, we can calculate the pOH:
\[
...