The theoretical molar yield of lead (II) chloride will be 9 moles.
First, we need to look at the equation of the reaction:
[tex]Pb^{2+} + 2Cl^- --- > PbCl_2[/tex]
From the equation, the 1 mole of Pb2+ ion requires 2 moles of Cl- ion in order to produce 1 mole of lead (II) chloride.
Thus, with 18 moles Cl- ions, 9 moles of Pb2+ would be needed, instead of 12 moles. Pb2+ is simply in excess while Cl- can be said to be limiting.
Therefore, Cl- will determine how much of lead (II) chloride that will be produced. The ratio is 2 moles of Cl- to 1 mole of lead (II) chloride.
With 18 moles Cl-, 9 moles of lead (II) chloride will, thus, be produced.
More on mole ratios can be found here: https://brainly.com/question/14425689
#SPJ1