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    0.167g sample of iron reacts with a stream of dry chlorine to form 0.487g of solid X. The molar mass of solid X was determined to be 324.6g/mol

    Calculate the molecular formula of X.

    RAM of iron - 55.8. RAM of chlorine 35.5.
    0.487-0.167=0.320grams of chlorine

    So 0.167/55.8 = 0.00299

    0.32/35.5 = 0.009014

    Ratio 0.00299:0.009014

    is 1:3 So empirical formula is FeCl3

    Why is the molecular formula Fe2Cl6?!
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    The molecular mass of FeCl3 is 162.3 g/mol so that can't be solid X. Multiplying everything by 2 to get Fe2Cl6, however, gives you 324.6 g/mol which you are told is the correct molar mass of sold X. If it's the structure of Fe2Cl6 you're concerned about, I guess it would be something similar to the Al2Cl6 dimer, like this: Name:  Fe2Cl6.gif
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    (Original post by Kyri)
    The molecular mass of FeCl3 is 162.3 g/mol so that can't be solid X. Multiplying everything by 2 to get Fe2Cl6, however, gives you 324.6 g/mol which you are told is the correct molar mass of sold X. If it's the structure of Fe2Cl6 you're concerned about, I guess it would be something similar to the Al2Cl6 dimer, like this: Name:  Fe2Cl6.gif
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    Thank you Very much!
 
 
 
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Updated: January 27, 2010
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