Question

Calculate the number of gold atoms in a 80.0 g sample of gold (III) chloride (Au2CI6)Be sure your answer has a unit symbol if necessary, and rounded to 3 significant digits

Answer 1

The number of gold atoms is 1.590x10^23.

- First, with the molar mass of Au2Cl6 (607g/mol) we can find the grams of Au in 80g of Au2Cl6:

`\begin{gathered} 607g\text{ of Au2Cl6 \_\_\_\_\_\_ 394g of Au} \\ 80g\text{ of Au2Cl6 \_\_\_\_\_\_ x= }(80g.394g)/(607g) \\ x=\text{ 51.93g} \end{gathered}`

Now we know that there are 51.93g of Au in 80g of Au2Cl6.

- Second, with the molar mass of gold (197g/mol) we can calculate the number of moles in 51.93g of gold:

`\begin{gathered} 197g\text{ \_\_\_\_\_ 1mol} \\ 51.93g\text{ \_\_\_\_ x= }(51.93g.1mol)/(197g) \\ x=0.264\text{mol} \end{gathered}`

Now we know that there are 0.264 moles of gold in the sample.

- Third, with the Avogadro's number (6.022*10^23) we can calculate the number of gold atoms in the sample:

`\frac{0.264mol.\mleft(6.022x10^(23)\mright)}{1\text{mol}}=1.590x10^(23)`

So, the number of gold atoms is 1.590x10^23.