how many fluorine atoms are found in 1.92 grams of AsF3?

Question

anonymous · Answer

To know the number of atoms found in 1.92 g of AsF3, you need first to get the number of moles equivalent to this mass. The number of moles is calculatedby dividing the gviven mass by the molar mass of AsF3. 

Molar mass of AsF3= ((1) Molar Mass of As)+((3)(Molar mass of F))
                            = (74.92 g/mol) + ((3)(18.998 g/mol))
Molar mass of AsF3= 131.914 g/mol

Now, compute for the number of moles.
Number of moles of AsF3= (mass)/ molar mass
                                    = (1.92g)/(131.914g/mol)
Number of moles of AsF3= 0.01455493731 mol

Lastly, to get the number of atoms, you have to use the Avogadro's number, 6.022 x 10^23.

$$\frac{ 6.022  x  10^{23} atoms }{ mol }  x  0.01455493731 mol    of AsF3$$

solving that gives 8.765 x 10^21 atoms! :)