Chemistry Question: Precipitation Reaction

Question

Consider the following precipitation reaction: 2Na3PO4(aq)+3CuCl2(aq)→ Cu3(PO4)2(s)+6NaCl(aq)

 

What volume of 0.183 M Na3PO4 solution is necessary to completely react with 91.6 mL of 0.106 M CuCl2?

 

Answer 1

First find the moles of CuCl₂ by using the molarity, M (mol/L)

(91.6 mL /(1000 mL/L)) = 0.0916 L  --> 0.0916L(0.106 mol/L) = 9.71 x 10^-3 mol CuCl₂

 

Then use the mole ratio 2:3 Na₃PO₄:CuCl₂ from the equation to determine the number of moles of Na₃PO₄

9.71 x 10^-3 mol CuCl₂ (2 mol Na₃PO₄/3 mol CuCl₂)

= 6.47 x 10^-3 mol Na₃PO₄

 

And we know the molarity (mol/L) of the Na₃PO₄ solutions, so we solve for volume (V)

 

6.47 x 10^-3 mol / V = 0.183 M = 0.183 mol/L

 V = 6.47 x 10-3 mol/(0.183 mol/L)--> the volume will be in liters