Group 2: Alkaline earth metals
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What's the displayed formula for magnesium ethanoate? What is the mechanism for the reaction between magnesium and ethanoic acid?
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Corrie writes .....
Magnesium ethanoate is an ionic compound, consisting of Mg2+ ions and ethanoate ions, CH3COO-, in a 1:2 ratio, giving the formula: Mg(CH3COO)2.
I can't unfortunately draw a structure for the ethanoate ion on this email, but I can describe it. It consists of a C=O group to which is attached a CH3- group and a -O- (where the H in the acid was attached). You should try and draw this out showing all the bonds yourself - easy if you can draw the displayed formula of ethanoic acid.
This reaction is the typical reaction of a metal with the H+ ions provided by an acid, to produce hydrogen and a salt derived form the acid. It is therefore a redox reaction, the Mg supplying electrons to reduce the H+ ions to H2:
Mg -> Mg2+ + 2e-
2H+ + 2e- -> H2
A detailed mechanism for this reaction is a mattter for much speculation - I suggest you read the article by Hacker & Williams referred to in our tutorial 'Metal-acid reactions: a second tutorial ' if you are interested. You can find the tutorial via the Practical Investigations link on the Re:act Homepage. You will also find discussion of this isue in past FAQs to this site, which you can also find via the link above.
Risk assessment
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For further guidance see our tutorial on Risk Assessment.
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updated: 01 April 2008
