Question

A solution of ammonia and water contains 1.20×1025 water molecules and 8.30×1024 ammonia molecules. How many total hydrogen atoms are in this solution?

Answer 1

Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles. We calculate as follows:

 1.20×10^25 water molecules ( 2 atoms H / 1 molecule H2O ) + (8.30×1024 ammonia molecules ( 3 atoms H / 1 molecules NH3 ) = 4.89x10^25 atoms H