How many total atoms are in .660 g of #P_2O_5#?

1 Answer

Answer:

#14 xx 10 ^21# atoms

Explanation:

Let us first calculate the number of moles of Phosphorous (#V#) Pentoxide i.e. #P_2O_5#

mass of #P_2# #O_5# = #0.660# #g#

molar mass of #P_2# #O_5# = #142# #g# #mol^-1#

#"number of moles of"# #P_2# #O_5# = #"mass" /"molar mass"#

#n = 0.660 / 142# #g# #mol^-1#

#n = 0.0046# #mol# of #P_2# #O_5#

one mole of #P_2# #O_5# has 5 moles of Oxygen atoms.

using this we can write two conversion factors

1 mol #P_2# #O_5#/ 5 mol Oxygen or 5 mol Oxygen / 1 mol #P_2# #O_5#

using conversion factor

#0.0046# #mol# of #P_2# #O_5# x #[ (5 " mol " O_2 ) /( 1 " mol " P_2O_5)]#

= #0.023# #mol# of Oxygen

#0.023# #mol xx 6.02 xx 10 ^23# #"atom"# / #mol#

= #14 xx 10 ^21# #"atoms"#