Question

Calculate how many milliliters of 0.150 M Na3PO4 solution are necessary to turn all of the copper in 35.0 mL of 0.837 M CuCl2 solution into solid Cu3(PO4)2 product.

Answer 1

Na3PO4 +CuCl2 react

They exchange their ions to get

NaCl + Cu3(PO4)2

Making our reaction

Na3PO4 + CuCl2 —> NaCl + Cu3(PO4)2

First, balance the reaction.

Then calculate how many moles CuCl2 are in 35 mL of 0.837M. Remember that M, molarity, is moles per L, so convert 0.35 mL to L and then multiply molarity* volume

Then use the balanced equation to find the mole ratio between CuCl2 and Na3PO4

Use that ratio to convert moles CuCl2 to moles Na3PO4

Finally, since you know that your Na3PO4 solution is 0.150M, you can set 0.150M = (moles Na3PO4) / (L Na3PO4) and solve for L Na3PO4. Since you were given mL CuCl2 it would be a good idea to convert your volume Na3PO4 to mL to stay consistent.