Answer: 197 grams
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.
To calculate the moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar Mass}}=[/tex]
Given mass = 405 g
Molar mass = 78.07 g/mol
[tex]\text{Number of moles}=\frac{405g}{78.07g/mol}=5.19moles[/tex]
1 mole of [tex]CaF_2[/tex] contains = 2 moles of fluorine
5.19 mole of [tex]CaF_2[/tex] contains = [tex]\frac{2}{1}\times 5.19=10.38moles[/tex] of fluorine
Mass of flourine =[tex]moles\times molar mass=10.38\times 19=197g[/tex]
Thus 197 grams of F are in 405 grams of [tex]CaF_2[/tex] .
