CHEM 111 Week 5 Lecture Notes
CHEM 111 Week 5 Lecture Notes 111/40551
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This 9 page Class Notes was uploaded by firstname.lastname@example.org Notetaker on Friday October 9, 2015. The Class Notes belongs to 111/40551 at University of St. Thomas taught by Uzcategui-White in Summer 2015. Since its upload, it has received 16 views.
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Date Created: 10/09/15
Chemistry Week 5 Lecture Notes Chapter 4 3 Types of Chemical Reactions 1 Precipitation 2 Acid Base 3 Oxidation Reduction redow combination decomposition displacement combustion 0 Water as a Solvent 0 Aqueous solutions compounds dissolved in water homogeneous mixture 0 Polar Molecule Uneven electron distribution Bent molecular shape 0 Dissolves ionic compounds all covalent compounds most 0 Water interacts strongly with its solutes and often plays an active role in aqueous solutions 0 Ex NaCl 5 9 Na aq Cl aq Ionic bond Interacts with a molecule of water Sugar C12H22012 Covalent bond Whole molecule interacts with water 0 Strong electrolytes substances that dissolve completely in water and produce ions They conduct electricity which requires the presence of ions Ex salt ionic compounds strong acidsbases 0 Weak electrolytes substances that do not completely dissolve in water formation of ions ex weak acidsbases CH3COOH acetic acid Gatorade 0 Non electrolytes dissolve in water without formation of ions doesn t conduct electricity ex covalent compounds sugar 3 Types of Equations 1 Molecular Shows all reactant and products as if they were intact undissociated compounds breaks apart all aqueous Ex AgN03 aq NaCl aq 9 AgCl s NaN03 aq 2 Total Ionic Shows all soluble ionic substances dissociated into ions Ex Ag aq N03 aq Na aq Cl aq 9 AgCl s Na aq N03 aq 3 Net Ionic eliminates the spectator ions and shows only the actual chemical reactions Ex Ag aq Cl aq 9 AgCl 5 Problem 412 How many total mols of ions are released when the following dissolved in water 688 x 1043 g NiBr2 x 3H20 Total mols of Ions NiBr2 x 3H20 9 Ni 2 aq ZBr aq 3H20 l Mols NiBr2 x 3H20 688 x 10quot3g NiBr2 x 3H20 24249 g mol 252 x 1045 mol NiBr2 x 3H20 Mols Ni 252 x 10 quot5 mols NiBr2 x 3H20 x 1 mol Ni 1 mol NiBr2 x 3H20 252 x 10 quot5 mol Ni Mols Br 252 x 10 quot5 mols NiBr2 x 3H20 x 2 mol Br 1 mol NiBr2 x 3H20 504 x 1045 mol Br 504x 10 quot5 252 x 1045 757 x 10 quot5 mol of ions Problem 421 Write a total ionic and a net ionic equation 2HBr aq CaOH2 aq 9 2H20 I CaBr2 aq total ionic 2H aq ZBr aq Ca2 aq 20H aq 9 2H20 I Ca2 aq ZBr aq net ionic 2H aq 20H aq 9 2H20 I 0 Different types of reactions 1 Precipitation two aqueous ionic compounds react to produce a water insoluble solid product known as precipitate Predicting whether a precipitate will form Look at ions in each compound Look at table 41 will be given Problem 425 Complete precipitation reaction with balanced molecular total and net ionic equations CaCl2 aq Cs3PO4 aq 9 Ca3PO4 s CsCI aq o Precipitation reaction ionic aq ionic aq 9 ionic s ionic aq 0 Molecular total ionic and net ionic 0 Strong weak and non electrolytes Acid Base Reactions 0 Acid reacts with a base water is a reactant or a product Acid substance that produces H or H30 ions when dissolved in water Base produces OH ions Acid HCI aq 9 H aq Cl aq HCI aq H20 I 9 H30 aq Cl aq Base NaOH aq 9 Na aq OH aq Strong acid complete dissociation into ions good conductors strong electrolytes Weak Acids do not completely dissociate weak electrolytes Know Table 42 in Book Strong base from group 1A or 2A Weak base NH3 ex NH3 aq H20 l 9 OH aq NH4 aq Acid Base reactions form water H20 l salt aq Neutralization reaction HCI aq NaOH aq 9 H20 l NaCl aq Total ionic H aq Cl aq Na aq OH aq 9 H20 l Na aq Cl aq Net ionic H aq OH aq 9 H20 l Weak acid example CH3COOH aq KOH aq 9 CH3COOH aq KOH aq 9 H20 l CH3COOK aq Total CH3COO aq K aq OH aq 9 H20 l CH3COO aq K aq Net H aq OH aq 9 H20 l Precipitation 9 solid Acid Base 9 solid Problem 439 Complete the acid base reaction with balanced molecular total and net ionic equations a Cesium Hydroxide aq nitric acid aq 9 CsOH aq HN03 aq 9 H20 l CsN03 aq Total Cs aq H aq N032 aq 9 H20 l Cs aq N032 aq Ionic 0H aq H aq 9 H20 l Quantifying Acid Base Reactions by Titration o Titration using the concentration of one solution by the concentration of another 1 Equivalence point of moles of acid of moles of base 2 End Point the reaction is complete ndicator weak acid H X color 1 base 9 X color 2 Problem 442 If 2598 mL of 01180 M of KOH solution reacts with 5250 mL of CH3CO0H solution what is the molarity of the acid solution CH3CO0H aq KOH aq 9 H20 l CH3CO0K aq Moles of base moles of acid Mols KOH 1180 M x 02598 L 003605 mol KOH Mols of acid 003605 mol CH3CO0H M 003605 mol 05250 L 05899 M Example without a 11 Ratio 21 H2504 aq 2KOH aq 9 2H20 l K2504 aq Mols KOH 003605 mol KOH Mols H2504 003605 mol KOH x 1 mol H2504 2 mols KOH 00180 mol H2504 Molarity 00180 mol 05250 L 0343 mol L Redox Reactions oxidation reduction 0 Net movement of electrons from one reactant to another Oxidation losing electrons more positive Reduction gaining electrons more negative EX ionic 2 Mgs OZ g 9 2MgO s Redox 9 ionic compound or a molecularcovalent compound Example is ionic metal with a nonmetal 2 Mg 5 OZ g 9 2MgO s Mg2 02 Mg 0 9 Mg 2 loses 2 electrons OZ 0 9 OZ gains 2 electrons Oxidized Mg reducing agent Reduced OZ oxidizing agent EX covalent 2 nonmetals H2 g Cl2 g 9 2HC g H2 0 9 H2 1 Cl2 0 9 Cl2 1 H2 oxidizing more Cl2 reducing more Always look at reactant side to determine who is the oxreducing agent Oxidation Numbers ON o The charge the atom will have if the electrons were transferred completely 0 General Rules 1 Atom in elemental form ON 0 2 Monoatomic ion ON ion charge 3 Oxygen peroxide H202 ON 1 all other compounds ON 2 4 Group highest ON lowest ON Problem 450 Give the oxidation of nitrogen in the following a NHZOH b N2F2 H2 1 x 2 2 0 2 x 1 2 H 1 x 1 1 2 2 1 set equal to 0 means N will equal 1 b N2 F4 1 x 4 4 N2 4 2 N 2 c N H4 1 x 4 4 plus charge at the end of NH4 means charges have to equal 1 N 3 Problem 456 Identify the oxidixing and reducing agents in the following a 5H2C204 2MnO4 6H 9 2Mn 2 10C02 8H20 1 find oxidation numbers for each of the following 2 determine which amount changes from reactant to product more or less postivive H nothing changes C 3 9 4 more positive oxidixzed reducing agent C2H204 0 nothing changes Mn 7 9 2 less positive reduced oxidizing agent MnO4 always look at reactants for answers b 3Cu 8H 2N03 9 3Cu 2 2N0 4H20 oxidized reducing agent Cu Reduced oxidizing agent N03 Do NOT include coefficient in answer Elements in Redox Reactions o Classified according to the number of reactants and products a Combustion redox 2 elements or 1 element plus 1 compound b Decomposition Redox thermal electrolytic c Displacement Redox single displacement d Combustion Combination Reaction 0 Two or more reactants will combine to form one product 0 Two elements 1 Metal nonmetal 9 ionic 2 Nonmetal nonmetal 9 covalent Ex 2 Ag 5 18 58 s 9 AgZS s ionic 18 58 s 02 g 9 502 g covalent Compound Element Ex 2N0 g 02 g 9 2N02 g Decomposition Reaction o Opposite of combination reaction bigger substance is broken apart Thermal heat Electrolyticelectricity Ex thermal 2KC03s 9 2KC s 302 g electrolytic ZHZO l 9 2H2 g 02 g