Help chemistry

I don’t get why I add and minus 2 lots of the moles of Magnesium…
Because the Mg2+ doesn’t have a coefficient 2/ balancing number 2 because when It reacts with Ch3Coo- you get Mg(CH3COO)2
It’s the CH3COO that’s multiplied by 2 right?? Part iii

(edited 11 months ago)

Reply 1

user23184

This is what I gathered from the question, hope it makes sense:

The equation for the reaction would be
C2H5COOH <=> Mg(C2H5COO)2 + 2H+

When working out the moles of both C2H5COOH and C2H5COO-, you're looking at the molar ratio, where the ratio of both C2H5COOH and C2H5COO- to Magnesium is 2:1.
Therefore, when working out the moles of C2H5COOH and C2H5COO-, you must find the moles of Mg (which you have) and multiply by two, as for every mole of Mg, there are two moles of C2H5COOH and C2H5COO-.

I'm not sure if anything is included in the mark scheme but this seems to be what is taking place in the calculations