11 Precipitation Reactions When one mixes ions that form compounds that are insoluble (as could be predicted by the solubility guidelines), a precipitate is formed.
12 Three Types of Equations Molecular Equation- written as whole formulas, not the ions.K2CrO4(aq) + Ba(NO3)2(aq) ®Complete Ionic equation show dissolved electrolytes as the ions.2K+ + CrO4-2 + Ba+2+ 2 NO3- ®BaCrO4(s) + 2K+ + 2 NO3-Spectator ions are those that don’t react.
13 Three Type of Equations Net Ionic equations show only those ions that react, not the spectator ionsBa+2 + CrO4-2 ® BaCrO4(s)Write the three types of equations for the reactions when the following solutions are mixed.
14 Precipitation reactions Molecular…..NaOH(aq) + FeCl3(aq) ®Ionic ….Na+(aq)+OH-(aq) + Fe+3 + Cl-(aq) ®So all that really happens is …..
15 Precipitation reaction Try this one….Li2CO3(aq) + Ba(NO3)2(aq) ®
17 Precipitations Reactions Only happen if one of the products is insolubleOtherwise all the ions stay in solution- nothing has happened.Need to memorize the rules for solubility
18 iron (III) sulfate and potassium sulfide Lead (II) nitrate and sulfuric acid.
19 Stoichiometry of Precipitation What mass of solid is formed when mL of 0.100M Aluminum chloride is mixed with mL of 0.100M sodium hydroxide?
20 25 mL of 0. 67 M of H2SO4 is added to 35 mL of 0. 40M SrCl2 25 mL of 0.67 M of H2SO4 is added to 35 mL of 0.40M SrCl2 . What mass of SrSO4 is formed?
21 What volume of M HCl is needed to precipitate the silver from 50.ml of M silver nitrate solution ?
22 AcidsArrhenius defined acids as substances that increase the concentration of H+ when dissolved in water.Brønsted and Lowry defined them as proton donors.
23 Acids There are only six strong acids: Hydrochloric (HCl) Hydrobromic (HBr)Hydroiodic (HI)Nitric (HNO3)Sulfuric (H2SO4)Perchloric (HClO4)
24 BasesArrhenius defined bases as substances that increase the concentration of OH− when dissolved in water.Brønsted and Lowry defined them as proton acceptors.
25 Bases The strong bases are the soluble metal salts of hydroxide ion: Alkali metalsCalciumStrontiumBarium
26 Acid-Base ReactionsIn an acid-base reaction, the acid donates a proton (H+) to the base.
27 Neutralization Reactions Generally, when solutions of an acid and a base are combined, the products are a salt and water.CH3COOH (aq) + NaOH (aq) CH3COONa (aq) + H2O (l)
28 Neutralization Reactions When a strong acid reacts with a strong base, the net ionic equation is…HCl (aq) + NaOH (aq) NaCl (aq) + H2O (l)
29 Neutralization Reactions When a strong acid reacts with a strong base, the net ionic equation is…HCl (aq) + NaOH (aq) NaCl (aq) + H2O (l)H+ (aq) + Cl- (aq) + Na+ (aq) + OH-(aq) Na+ (aq) + Cl- (aq) + H2O (l)
30 Neutralization Reactions When a strong acid reacts with a strong base, the net ionic equation is…HCl (aq) + NaOH (aq) NaCl (aq) + H2O (l)H+ (aq) + Cl- (aq) + Na+ (aq) + OH-(aq) Na+ (aq) + Cl- (aq) + H2O (l)H+ (aq) + OH- (aq) H2O (l)
31 A 50. 00 mL sample of aqueous Ca(OH)2 requires 34. 66 mL of 0 A mL sample of aqueous Ca(OH)2 requires mL of M Nitric acid for neutralization. What is molarity of Ca(OH)2 ?
32 75 mL of 0. 25M HCl is mixed with 225 mL of 0. 055 M Ba(OH)2 75 mL of 0.25M HCl is mixed with 225 mL of M Ba(OH)2 . What is the concentration of the excess H+ or OH- ?
33 Gas-Forming Reactions Some metathesis reactions do not give the product expected.In this reaction, the expected product (H2CO3) decomposes to give a gaseous product (CO2).CaCO3 (s) + HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (l)
34 Gas-Forming Reactions When a carbonate or bicarbonate reacts with an acid, the products are a salt, carbon dioxide, and water.CaCO3 (s) + HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (l)NaHCO3 (aq) + HBr (aq) NaBr (aq) + CO2 (g) + H2O (l)
35 Gas-Forming Reactions Similarly, when a sulfite reacts with an acid, the products are a salt, sulfur dioxide, and water.SrSO3 (s) + 2 HI (aq) SrI2 (aq) + SO2 (g) + H2O (l)
36 Gas-Forming Reactions This reaction gives the predicted product, but you had better carry it out in the hood, or you will be very unpopular!But just as in the previous examples, a gas is formed as a product of this reaction.Na2S (aq) + H2SO4 (aq) Na2SO4 (aq) + H2S (g)
37 Oxidation-Reduction Reactions An oxidation occurs when an atom or ion loses electrons.A reduction occurs when an atom or ion gains electrons.One cannot occur without the other.
38 Oxidation NumbersTo determine if an oxidation-reduction reaction has occurred, we assign an oxidation number to each element in a neutral compound or charged entity.
39 Oxidation NumbersElements in their elemental form have an oxidation number of 0.The oxidation number of a monatomic ion is the same as its charge.
40 Oxidation NumbersNonmetals tend to have negative oxidation numbers, although some are positive in certain compounds or ions.Oxygen has an oxidation number of −2, except in the peroxide ion in which it has an oxidation number of −1.Hydrogen is −1 when bonded to a metal, +1 when bonded to a nonmetal.
41 Oxidation NumbersNonmetals tend to have negative oxidation numbers, although some are positive in certain compounds or ions.Fluorine always has an oxidation number of −1.The other halogens have an oxidation number of −1 when they are negative; they can have positive oxidation numbers, however, most notably in oxyanions.
42 Oxidation NumbersThe sum of the oxidation numbers in a neutral compound is 0.The sum of the oxidation numbers in a polyatomic ion is the charge on the ion.
43 Oxidation StatesAssign the oxidation states to each element in the following.CO2 NO3H2SO4 Fe2O3Fe3O4
44 Oxidation-ReductionTransfer electrons, so the oxidation states change.Na + 2Cl2 ® 2NaClCH4 + 2O2 ® CO2 + 2H2OOxidation is the loss of electrons.Reduction is the gain of electrons.OIL RIGLEO GER
45 Oxidation-ReductionOxidation means an increase in oxidation state - lose electrons.Reduction means a decrease in oxidation state - gain electrons.
46 Identify the Substance oxidized Substance reduced Fe (s) + O2(g) ® Fe2O3(s)
48 Half-ReactionsAll redox reactions can be thought of as happening in two halves.One produces electrons - Oxidation half.The other requires electrons - Reduction half.
49 Write the half reactions for the following. Na + Cl2 ® Na+ + Cl- SO3-2 + H+ + MnO4- ® SO4-2 + H2O + Mn+2
50 Balancing Redox Equations In aqueous solutions the key is the number of electrons produced must be the same as those required.For reactions in acidic solution an 8 step procedure.Write separate half reactionsFor each half reaction balance all reactants except H and OBalance O using H2O
51 Acidic Solution Balance H using H+ Balance charge using e- Multiply equations to make electrons equalAdd equations and cancel identical speciesCheck that charges and elements are balanced.
55 Basic solution Follow steps for acidic solution Upon completion, add as many OH- ions as there are H+ ions to both sides of the equationThe side of the equation with both H+ and OH- combine to form waterIf necessary reduce the waters on both sides of the equation
56 Displacement Reactions In displacement reactions, ions oxidize an element.The ions, then, are reduced.
57 Displacement Reactions In this reaction,silver ions oxidizecopper metal.Cu (s) + 2 Ag+ (aq) Cu2+ (aq) + 2 Ag (s)
58 Displacement Reactions The reverse reaction,however, does notoccur.Cu2+ (aq) + 2 Ag (s) Cu (s) + 2 Ag+ (aq)x
59 Mixing a SolutionTo create a solution of a known molarity, one weighs out a known mass (and, therefore, number of moles) of the solute.The solute is added to a volumetric flask, and solvent is added to the line on the neck of the flask.
60 Dilution One can also dilute a more concentrated solution by Using a pipet to deliver a volume of the solution to a new volumetric flask, andAdding solvent to the line on the neck of the new flask.
61 DilutionThe molarity of the new solution can be determined from the equationMc Vc = Md Vd,where Mc and Md are the molarity of the concentrated and dilute solutions, respectively, and Vc and Vd are the volumes of the two solutions.
62 Using Molarities in Stoichiometric Calculations