How many atoms of Chlorine are present in 0.072g of FeCl3?

1 Answer
Sep 3, 2017

Answer:

Approx. #8xx10^20# individual chlorine atoms...........

Explanation:

We (i) take the ration of the mass of the sample to the formula mass of #FeCl_3# to get the number of moles of #FeCl_3#.

#(0.072*g)/((55.85+3xx35.46)*g*mol^-1)=4.44xx10^-4*mol#.

And thus we have a molar quantity with respect to #FeCl_3#...the molar quantity with respect to #Cl# is CLEARLY three times this figure, i.e. #4.44xx10^-4*molxx3=1.33xx10^-3*mol#.....

But (ii) a mole specifies #"Avogadro's number"# of individual items of stuff, i.e. #N_A-=6.022xx10^23*mol^-1#.

And so ..........

#"number of chlorine atoms"=6.022xx10^23*mol^-1xx1.33xx10^-3*mol=??#