Mg reacting with acids: molar enthalpy and reaction rate

[Physics103]

question answered - thanks

Thank you for your help

 

[mrjeffy321]

You have 3 acids listed (Hydrochloric acid, Sulfuric acid, and Acetic acid), for this reaction we will assume they are all at the same molar concentration.

One thing to note is that Acetic is a weak acid (incomplete disassociation of its ions in solution), whereas Hydrochloric and sulfuric are strong acids (almost total disassociation of ions in solution). For this reason, I think we can rule out Acetic acid as a possibility for the fastest reaction.

So now it is between HCl and H2SO4. Since we assume they are at the same molar concentration (meaning that for ever X mL of acid, there are equal number of moles of either HCl or H2SO4), I would think that Sulfuric acid will react the fastest with Mg. This is because for every 1 mole of H2SO4, you have 2 moles of H+ in solution, and with twice the number of H+ ions in solution, you are much more likely to get a quicker reaction with a material such as Magnesium.