A sample of a compound with nitrogen and hydrogen has 7.207g N and 1.037g H. Molar mass of compound is 32 g. What is its molecular formula?

I tried this and my answer was N4H8 but I was incorrect. Anyone know how to do this?

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  • 2 months ago

    moles of N in your sample = 7.207g / 14 g/mol = 0.515 moles 

    moles of H = 1.037g / 1.004 g/mol  = 1.033 moles

    molar ratio N:H = 0.514:  1.033 or 1:2

    empirical formula is the molar ratio of the elements or NH2

    empirical formula mass = 16 g (14+2) 

    molar mass is given as 32 g / mole so there are 2 empirical formula mass units / mol of your compound 

    so 2 * NH2 = N2H4 .. 

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  • KennyB
    Lv 7
    2 months ago

    N4H8 has a molar mass of 72 - your answer should be N2H4

    • Roger the Mole
      Lv 7
      2 months agoReport

      You are correct to point out that N2H4 does not meet the requirement in the question, but 72 is not the number.  You seem to have counted the hydrogens twice.

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