Exp' 8 Objectives

1
Exp. 8 Objectives

• To determine the limiting reactant in a mixture
  of two soluble salts.
• To determine the percent composition of each
  substance in the mixture.
• Salt-an ionic compound formed by an acid/base
  neutralization where the cation is not H and the
  anion is not OH-.

2
Exp. 8 Introduction

• Two basic factors affect the yield of products in
  a chemical reaction
• the amounts of starting materials (reactants)
• the percent yield of the reaction.
• Percent yield actual yield x 100
• theoretical yield

3
Exp. 8 Introduction

• Because chemicals react according to fixed mole
• ratios (stoichiometrically), only a limited
  amount of
• product can form from given amounts of starting
• materials.
• 2Na2PO412H2O(aq) 3BaCl22H2O(aq) ?
  
• Ba3(PO4)2(s) 6NaCl(aq)
  30H2O(l)
• The reactant that determines the amount of
  product is the limiting reactant.

4
Exp. 8 Procedural Notes

• Part A
• Step 2a. - warm the solution for 15 minutes DO
  NOT BOIL.
• Step 3. - Use vacuum filtering
• Step 5. - wash any remaining precipitate onto the
  filter paper with several (3-4) 5 mL volumes of
  warm DI-water.
• Step 6. - Dry in oven for 30 minutes.

5
Exp. 8 Procedural Notes

• Part B
• To test for excess PO43-, add BaCl2 to the test
  tube. If a ppt (Ba3PO4) forms, you had excess
  PO43- to react and Ba2 is the l.r.
• To test for excess Ba2, add Na3PO4 to the test
  tube. If a ppt (BaCl2) forms, you had excess
  Ba2 to react and PO43- is the l.r.

6
Exp. 8 Report Sheet

• Questions 1 and 2
• Discuss 9A 10.