Question

How many O atoms are in 4.39 g of CO2?

Answer 1

Molar mass of CO2,

MM = 1*MM(C) + 2*MM(O)

= 1*12.01 + 2*16.0

= 44.01 g/mol

mass(CO2)= 4.39 g

number of mol of CO2,

n = mass of CO2/molar mass of CO2

=(4.39 g)/(44.01 g/mol)

= 9.975*10^-2 mol

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

= 9.975*10^-2 * 6.022*10^23 molecules

= 6.007*10^22 molecules

1 molecule of CO2 has 2 atoms of O

So,

atoms of O = 2*number of molecules of CO2

= 2*6.007*10^22 molecules

= 1.20*10^23 atoms

Answer: 1.20*10^23 atoms