Question

How do you use a periodic table to determine the mass of 1 mol of nitrogen gas molecules?

Answer 1

Find yourself a Periodic Table.......and there should be one beside you now if you are doing your chemistry homework........

Explanation:

The Periodic Table lists (i) the atomic symbol, (ii) the atomic number, `Z`, and (iii) the atomic mass with units of `g*mol^-1`. You will always be issued a copy of the Periodic Table in a chemistry or physics exam.

For nitrogen, `Z=7`, and the atomic mass is listed as `14.01*g*mol^-1`. Since elemental nitrogen is a diatomic element, (in fact ALL the elemental gases SAVE the inert gases are diatomic, i.e. `X_2`), the mass of gaseous nitrogen is `28.02*g*mol^-1`.

Note that you simply have to KNOW that it is `"dihydrogen, dioxygen, dinitrogen, difluorine, dichlorine etc"`. `H_2`, `N_2` etc. are the standard states of these elements under standard conditions. You would not be told this normally (certainly not if you are an undergrad!).