Question

If you have 3.0*10^20 molecules of H2O Find the mass of the given quantity

Answer 1

1 moles contains 6.02*10^23 moles (avogadros constant number)
1--->6.02*10^23
xmoles--->3.0*10^20
3.0*10^20*1/6.02*10^23=0.00049833887 moles
Number of moles=mass(g)/Molar Mass (g/mol)
Molar Mass of H2O: (2*1)+(16*1)=18grams/mol
Mass of H2O:0.00049*18=0.00897grams