Chemistry Help Please??

Question

C7H5(NO2)3

How can I find out the number of grams, number of moles, and number of N atoms, by only knowing that there are 1.24x10^28 molecules?

Any help is greatly appreciated!!

Answer 1

Here is the answer from a similar problem just asked a few minutes ago:

# of molecule = 7.5 x 10^22 atoms / (3 atoms N/molecule)

# moles of molecule = # molecules of molecule /avogadro's number (molecules/mole)

# grams of molecule = # moles of molecule * molecular wt of molecule

While I appreciate that askers would like to get just the answer, I believe that those who answer should at least have them do the math! That way the asker has to evaluate the answer and get involved. Of course the asker will have to do some in this case as several of the answers are WRONG!

Answer 2

moles: 1.24x10^28 divided by 6.02x10^23

grams: number of moles multiplied by atomic mass of the molecule (atomic mass carbon*7+atomic mass hydrogen*5+etc)

atoms: molecules*(5+7+9)

Answer 3

molar mass=7*12+5*1+3*14+2*3*16=227

       in one mole no of molecules=6.022*10^23

       therefore 1.24*10^28 contains 1.24*10^28/6.022*10^23 grams

       no of mole = no of grams(above)/molar mass

       no of atoms=(7+5+3+6)*1.24*10^28(doubt)

      

       thank u good friend