Volume Molarity

Question

What volume in mL of 0.484 M Kbr is required to fully react with 69.41 mL of 0.183 M Pb(ClO4)2?

Answer 1

First, we must write the correctly balanced equation for the reaction:

2KBr(aq) + Pb(ClO₄)₂(aq) ==> 2KClO₄(aq) + PbBr₂(s) .. balanced equation

Next, find moles of Pb(ClO₄)₂ present:

moles Pb(ClO₄)₂ = 69.41 ml x 1 L / 1000 ml x 0.183 mol / L = 0.0127 mols Pb(ClO₄)₂ present

Next, find moles of KBr needed to react with 0.0127 mols Pb(ClO₄)₂:

moles KBr needed = 0.0127 mols Pb(ClO₄)₂ x 2 mol KBr / molPb(ClO₄)₂ = 0.0254 mol KBr needed

Finally, find the volume of KBr needed:

0.0254 mols KBr x 1 L / 0.484 mol KBr = 0.0525 L = 52.5 mls KBr needed