Respuesta :
The percent composition for Ca in CaCl2 is 36.1% and the percent composition for Cl in CaCl2 is 63.9%
1st) We need to know the atomic weight of Ca and Cl, and the molecular weight of CaCl2.
We can find the atomic weight in the Periodic Table:
Ca atomic weight: 40.07 g/mol
Cl atomic weight: 35.45 g/mol
So, the molecular weight of CaCl2 is:
40.07 g/mol x (35.45 g/mol x2) = 110.97 g/mol
CaCl2 molecular weight: 110.97 g/mol
2nd) With a mathematical Rule of Three we can calculate the percent composition for Ca and Cl. Here, it is important to rember that the CaCl2 molecular weight (110.97 g/mol) represents the 100%.
- Percent composition for Ca in CaCl2:
[tex]\begin{gathered} 110.97\text{ g/mol-100}\% \\ 40.07\text{ g/mol -x=}\frac{40.07\text{ g/mol}\cdot\text{100}\%}{110.97\text{ g/mol}} \\ x=36.1\% \end{gathered}[/tex]- Percent composition for Cl in CaCl2:
[tex]\begin{gathered} 110.97\text{ g/mol - 100}\% \\ 70.9\text{ g/mol - x=}\frac{70.9\text{ g/mol}\cdot\text{100}\%}{110.97\text{ g/mol}} \\ x=63.9\% \end{gathered}[/tex]So, the percent composition for Ca in CaCl2 is 36.1% and the percent composition for Cl in CaCl2 is 63.9%.
