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    I'm doing organic chemistry at the moment with ethanoic acid, but I don't understand why Magnesium ethanoate's salt is (CH3COOH)2Mg, but then Sodium ethanoate is C2H3NaO2. Why doesn't it have the CH3COOH formula like magnesium ethanoate? Need help fast, chemistry test tomorrow!!!!
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    (Original post by Howeller553)
    I'm doing organic chemistry at the moment with ethanoic acid, but I don't understand why Magnesium ethanoate's salt is (CH3COOH)2Mg, but then Sodium ethanoate is C2H3NaO2. Why doesn't it have the CH3COOH formula like magnesium ethanoate? Need help fast, chemistry test tomorrow!!!!
    It is just two different ways of writing the formula.

    First, let's correct the magnesium salt's formula as there are too many hydrogens. The formula is (CH3COO)2Mg because the ethanoic acid molecule loses one H+ when it forms compounds with metal ions.

    Ethanoate ion is CH3COO- but another way to write this is (C2H3O2)- . The second is just a more empirical way of writing the formula, the same number of atoms of each element are included.

    So the sodium salt is usually written in the same way as you have the magnesium salt, CH3COONa, but we can make it more empirical like the formula you have C2H3NaO2. You could actually write the elements in any order and it would be OK, not good practice but just about OK if you have the correct number of each atom.

    We usually use the CH3COONa style of formula because it tells us a bit about the structure of the molecule.
 
 
 
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