To determine how many formula units of copper(II) chloride ([tex]\( CuCl_2 \)[/tex]) are present in [tex]\( 17.6 \, \text{g} \)[/tex] of [tex]\( CuCl_2 \)[/tex], follow these step-by-step instructions:
1. Calculate the number of moles of [tex]\( CuCl_2 \)[/tex]:
- We need to use the molar mass of [tex]\( CuCl_2 \)[/tex], which is given as [tex]\( 134.45 \, \text{g/mol} \)[/tex].
- The formula for the number of moles is:
[tex]\[
\text{moles of } CuCl_2 = \frac{\text{mass of } CuCl_2}{\text{molar mass of } CuCl_2}
\][/tex]
- Substituting the given values:
[tex]\[
\text{moles of } CuCl_2 = \frac{17.6 \, \text{g}}{134.45 \, \text{g/mol}} \approx 0.1309 \, \text{mol}
\][/tex]
2. Determine the number of formula units of [tex]\( CuCl_2 \)[/tex]:
- To find the number of formula units, we will use Avogadro's number, which is [tex]\( 6.022 \times 10^{23} \, \text{units/mol} \)[/tex].
- The formula to find the number of formula units is:
[tex]\[
\text{formula units of } CuCl_2 = \text{moles of } CuCl_2 \times \text{Avogadro's number}
\][/tex]
- Substituting the values calculated and given:
[tex]\[
\text{formula units of } CuCl_2 = 0.1309 \, \text{mol} \times 6.022 \times 10^{23} \, \text{units/mol} \approx 7.88 \times 10^{22} \, \text{units}
\][/tex]
So, the number of formula units of [tex]\( CuCl_2 \)[/tex] in [tex]\( 17.6 \, \text{g} \)[/tex] of [tex]\( CuCl_2 \)[/tex] is approximately [tex]\( 7.88 \times 10^{22} \)[/tex].
Therefore, the correct answer is:
[tex]\[ 7.88 \times 10^{22} \, \text{formula units} \][/tex]
Thus, the answer is:
[tex]\[
\boxed{7.88 \times 10^{22} \, \text{formula units}}
\][/tex]
