Here's how to calculate the number of molecules in 0.0710 mol of NH3:

1. Avogadro's Number:

* Avogadro's number tells us the number of particles (atoms, molecules, etc.) in one mole of a substance. It's approximately 6.022 x 10^23 particles/mol.

2. Calculation:

* To find the number of molecules, we multiply the number of moles by Avogadro's number:

Number of molecules = (0.0710 mol NH3) * (6.022 x 10^23 molecules/mol)

* Calculate the result:

Number of molecules ≈ 4.28 x 10^22 molecules of NH3

Therefore, there are approximately 4.28 x 10^22 molecules of NH3 in 0.0710 mol.