Mix the following solutions in pairs Write down the solution pairs and record your results • Potassium Iodide • Barium Nitrate • Lead Nitrate • When finished, try Silver Nitrate with Potassium Iodide.
Precipitate Reactions • Precipitates • Solubility rules • Using the rules of solubility
Reaction of PbNO3 and KI • Lead II Nitrate and Potassium Iodide • Both are strong electrolytes • That means they completely dissociate into ions • Adding the solutions together will create something new… • A chemical change the evidence is the precipitate.
Pb (NO)3 Look closer at Lead (II) Nitrate • Strong Electrolyte • Ions completely dissociate into: • Lead Pb2+ ions • Nitrate NO3 - Ions
The KI does the same thing • Posassium K+ ions and Iodide I- ions form. They are floating around in the water. (an aqueous solution)
When the lead and the iodide ions come into contact, they form a precipitate • The precipitate falls to the bottom, spectator ions are left in solution
Solubility Rules: Always Always Soluble 1. Always Soluble: • Li+, Na+,K+, NH4+ • Group 1A(Alkali Metals) and ammonium compounds are soluble. • C2H3O2-, NO3-,ClO3-, ClO4- • Acetates, Nitrates, Chlorates, Perchlorates are all soluble.
The solubility rules: Usually soluble Exceptions AP/H (Ag) Silver: AgCl, AgBr, AgI (Pb) Lead (II) PbCl2, PbBr2, PbI2 (Hg) Mercury (I): Hg2Cl2, Hg2Br2, Hg2I2 • Cl-, Br-, I- Most chlorides, bromides and Iodides are soluble Exceptions CBS-PM Calcium, Barium, Strontium, Lead, Magnesium MgF2, CaF2, SrF2, BaF2Lead (II) PbF2 • F- • Most fluorides are soluble Exceptions CBS/PBS Calcium, Strontium, Barium, Lead (II) CaSO4 SrSO4 BaSO4 PbSO4 • SO42- • Most Sulfates are soluble
The solubility rules: Usually NOT Soluble O2-, OH- Most hydroxides and oxides are insoluble Exceptions: CBS CaO, Ca(OH)2 SrO, Sr(OH)2 BaO, Ba (OH)2 And the ‘always group’ of Alkali metals and Ammonium
The solubility rules: Insoluble Ions • Not soluble • CO32- PO43- SO32- S2- C2O42- CrO42- Exceptions: The things that are always soluble. Group 1A (Alkali Metals) Li2CO3, Na2CO3… etc Ammonium compounds (NH4)2CO3
Types of reactions • Remember net ionic equations?
Showing everything in the reaction vessel (beaker, well plate, test tube…
Sometimes parts of the equation do nothing but sit and watch. Spectators
Complete ionic vs. net ionic Sodium sulfate + Barium Chloride react to form Solid barium sulfate and Sodium chloride 2 Na+ (aq) + SO42- (aq) + Ba2+ (aq) + 2 Cl- (aq) BaSO4 (s) + 2 Na+ (aq) + 2 Cl- (aq) NaCl is a strong electrolyte, so it does not combine to form a solid
Stoichiometry in Aqueous Reactions What volume of 0.200 M copper (II) sulfate is required to react with 50.0mL if 0.100 M NaOH? • Write the net ionic equation Cu 2+ (aq) + 2 OH- (aq) Cu(OH)2(s)
What volume of 0.200 M copper (II) sulfate is required to react with 50.0mL if 0.100 M NaOH? find the moles of each reactant needed: nOH- = nCu2+ =