How many mole of `NH_4Cl` must be added to one litre of 1.0 M `NH_4OH` to have a buffer of pH= 9. `K_(NH_(4)OH)=1.8 xx 10^(-5)?`

Explanation

To solve the problem of how many moles of `NH4Cl` must be added to one liter of 1.0 M `NH4OH` to achieve a buffer with a pH of 9, we can follow these steps:

### Step 1: Understand the Buffer System
We have a weak base `NH4OH` (ammonium hydroxide) and its salt `NH4Cl` (ammonium chloride). This combination will create a basic buffer solution.

### Step 2: Calculate pOH from pH
Since we know the pH of the buffer is 9, we can calculate the pOH using the relationship:
\[ \text{pH} + \text{pOH} = 14 \]
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