Calculate the empirical formula of gold chloride which contains `35.1%` of chlorine. At mass of Au = 197.

Explanation

To calculate the empirical formula of gold chloride (AuCl) given that it contains 35.1% chlorine, we will follow these steps:

### Step 1: Determine the percentage of gold.
Since the total percentage must equal 100%, we can find the percentage of gold by subtracting the percentage of chlorine from 100%.

\[ \text{Percentage of Gold} = 100\% - 35.1\% = 64.9\% \]

### Step 2: Convert percentages to grams.
For the purpose of calculation, we can assume we have 100 grams of the compound. Therefore, we can convert the percentages to grams:

- Mass of Chlorine (Cl) = 35.1 grams
- Mass of Gold (Au) = 64.9 grams

### Step 3: Calculate the number of moles of each element.
To find the number of moles, we will use the formula:

\[ \text{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]

- Molar mass of Chlorine (Cl) = 35.5 g/mol
- Molar mass of Gold (Au) = 197 g/mol

Calculating the moles:

\[ \text{Moles of Cl} = \frac{35.1 \text{ g}}{35.5 \text{ g/mol}} \approx 0.988 \text{ moles} \]

\[ \text{Moles of Au} = \frac{64.9 \text{ g}}{197 \text{ g/mol}} \approx 0.329 \text{ moles} \]

### Step 4: Determine the simplest mole ratio.
Now we will find the simplest ratio of moles of Au to moles of Cl.

\[ \text{Ratio of Au to Cl} = \frac{0.329}{0.329} : \frac{0.988}{0.329} \approx 1 : 3 \]

### Step 5: Write the empirical formula.
From the simplest ratio, we can conclude that there is 1 atom of gold for every 3 atoms of chlorine. Therefore, the empirical formula of gold chloride is:

\[ \text{Empirical Formula} = \text{AuCl}_3 \]

### Final Answer:
The empirical formula of gold chloride is **AuCl₃**.

---