Question

How many molecules are contained in 1.30 mol O2
Answer in units of molec

How many molecules are in 1.70 mol He
Answer in units of molec

How many molecules are in 0.0800 mol NH3
Answer in units of molec

How many molecules are in 15.6 g NO2
Answer in units of molec

What is the mass of 3.64 mol of the element iron (fe)
Answer in units of g

Answer 1

To convert from moles to molecules, simply multiply the number of moles by the Avogadros number which is about 6.022 x 10^23 molecules / moles.

Taking the O2 for example:

molecules of O2 = 1.30 moles * (6.022 x 10^23 molecules / moles)

molecules of O2 = 7.83 x 10^23 molecules

I believe you can do for the rest. Just follow the same steps.

 

For the last question.

mass Fe = 3.64 mol * 55.85 g/mol = 203.29 g