Question

What is the TOTAL number of atoms in 10.26 g of Al2(SO4)3?

Answer 1

Molar mass of Al2(SO4)3,

MM = 2*MM(Al) + 3*MM(S) + 12*MM(O)

= 2*26.98 + 3*32.07 + 12*16.0

= 342.17 g/mol

mass(Al2(SO4)3)= 10.26 g

number of mol of Al2(SO4)3,

n = mass of Al2(SO4)3/molar mass of Al2(SO4)3

=(10.26 g)/(342.17 g/mol)

= 2.999*10^-2 mol

number of molecules = number of mol * Avogadro’s number

number of molecules = 2.999*10^-2 * 6.022*10^23 molecules

number of molecules = 1.806*10^22 molecules

Count of each element in compound is:

{Al=2, S=3, O=12}

Total number of atoms in 1 molecule = 17

number of atoms = number of molecules * Total number of atoms in 1 molecule

number of atoms = 1.806*10^22 * 17

number of atoms = 3.07*10^23