mass of Mg = 3 g

Atomic relative Mg (Ar) = 24 g/mole

mass of CH3COOH = 12 g

Molecular relative of CH3COOH (Mr) = 60 g/mole

Reaction occurs:

Mg + 2CH3COOH → (CH3COO)2Mg + H2 (balance)

• first, calculate mole for each reactant

• identifying the limiting reactant from balanced equation, use the mole from calculation before and use coefficient for each reactant from balanced equation

use CH3COOH as limiting reactant because it has smallest mole quantity, so for 1 coefficient of each compoundcompound is 0,1 mole.

• calculate the remaining reactant

Mg + 2CH3COOH → (CH3COO)2Mg + H2

initial 0.125 0.2 - -

reacted 0.1 0.2 0.1 0.1

excess 0.025 - 0.1 0.1

• calculate mass of excess reactant, Mg