In the reaction MgCl2 plus 2KOH gives magnesium hydroxide plus 2KCl if 3 moles of MgCl2 are added to 4 moles KOH what determines how much magnesium hydroxide is made?

Answer 1

MgCl2(aq) + 2KOH(aq) --> Mg(OH)2(s) + 2KCl(aq)It is the molar ratio in the equation. Every mole of magnesium chloride requires 2 moles of potassium hydroxide. Thus 3 moles would need 6 moles of alkali for complete reaction. We don't have that much, so potassium hydroxide is the limiting reactant and we can only use 2 moles of the magnesium chloride and produce 2 moles of magnesium hydroxide.