Question

Determine the molecular weight for Mg(NO3)2

Answer 1

Use the periodic table to solve this out:
To get molecular weight (aka molar mass), what you have to do is find the molar masses of each constituent element of this compound, and add them up

Answer 2

So I will do this one for you:

ex. CO2

MW[C] = 12.01g/mol <-- the atomic mass part of your periodic table can be also interpreted as g/mol.

MW[O] = 16g/mol

Now, adding these two up:

MW[CO2] = MW[C]*2 + MW[O]
^- we multiplied by 2 for MW[C] because there are 2 C-atoms.

Answer 3

Nice explanation! I think - there might be a tiny typo? Aren't there 2 Oxygens, not 2 Carbons?

Answer 4

Yes you are correct. Sorry about that