1. R EACTIONS IN A QUEOUS S OLUTIONS : M ETATHESIS R EACTIONS AND N ET I ONIC E QUATIONS Experiment 21 Page 227 Dr. Scott Buzby, Ph.D.

2. O BJECTIVES To become familiar with writing equations for metathesis reactions Understand the difference between molecular, ionic and net ionic equations Determine the solubility of a salt by using solubility rules Study the effect of temperature on solubilty

3. D EFINITIONS Solubility The property of a substance to dissolve in another substance to form a homogenous solution Solute – The substance being dissolved Solvent – The substance doing the dissolving Aqueous solution – A solution where water is the solvent Homogenous solution – A stable mixture that is uniform in composition where the solute will not settle out, no matter how long the solution sits, and it cannot be removed by physical means (ex. filtering) Saturation The point at which no more solute can dissolve in a solution and additional amounts of it will appear as a precipitate. Precipitate the formation of a solid in a solution Electrolyte any substance containing free ions that make the substance electrically conductive (ionic solution)

4. M ETATHESIS R EACTION An aqueous chemical reaction in which the cations (+ Ions) and anions (- ions) appear to change partners In order for a net change in the solution to occur (i.e. a reaction), ions must be removed from the solution by the formation of a precipitate a weak electrolyte or nonelectrolyte a gas that escapes from solution

5. M ETATHESIS R EACTION C ON ’ T. Formation of a Precipitate Formation of a Gas Formation of a Weak Electrolyte

6. I ONIC AND N ET I ONIC E QUATIONS Molecular Equation Ionic Equation Net Ionic Equation

7. P ROCEDURE Part A: Metathesis Reactions Mix the solutions in small test tubes and record your observations (precipitate, gas bubbles, heat, nothing) on the report sheet Write out the three reactions according to your observations Skip reactions 6 - 9 & 14 - 15

8. P ROCEDURE C ON ’ T. Part B: Solubility, Temperature and Crystallization Prepare the solution as per instructions on Pg. 231 Cool the solution to ~10°C by dipping beaker into ice water ( DO NOT add ice to solution) and stirring carefully Observe shape of crystals and filter COLD solution into an evaporating dish Evaporate filtrate to half of its volume using a Bunsen burner and a ring stand (additional crystals should form) Filter HOT solution into 100mL beaker and compare shape of crystals with first batch Cool the filtrate to ~10°C with ice while stirring to obtain a third batch of crystals and compare shape with other two batches.

9. H OMEWORK – D UE N EXT W EEK Part A Report Sheet – Pages 233 – 236 Part B Solubility Graph – Page 235 Questions – Pages 235 – 236 Questions Page 236 Pre-lab Experiment #22 – Page 243