Chem 1211 1st Edition Lecture 10 Outline of Last Lecture I. Acids and BasesII. Conjugate Acid-Base PairsOutline of Current Lecture I. Oxidation-Reduction ReactionsII. Stoichiometry Current LectureI. Oxidation-Reduction Reactionsa. Oxidation: loss of e-b. Reduction: gain of e-c. Oxidation number for individual atomsi. Atoms, molecular elements in standard form: oxidation number=0ii. Ions- oxidation number= chargeiii. Common values1. H+=1+2. F=-13. O=-2iv. ConcepTest: Which oxidation numbers are correct for the indicated atom?1. Oxygen in O2, ON= 02. Oxygen in HO-, ON= -13. Oxygen in CO2, ON=-2a. ANSWER: 1 and 3 are correct. When by itself, an atom/molecule has a charge of 0; otherwise oxygen has a charge of -2v. Reactions with oxygen are oxidation reactions 1. ConcepTest: Which elements get oxidized and reduced, respectively, in the equation 2Fe2O3(s)+3 C(s) 4Fe(s)+3CO2(g)?a. Iron, oxygenb. Carbon, ironc. Carbon, oxygenThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.d. Iron, carboni. ANSWER: B. Oxygen is -2, so iron in the 2Fe2O3 must have an oxidation number of +3. On the otherside, 4 Fe has an oxidation number of 0. Since it goes from +3 to 0, it is reduced. Carbon is oxidized. 2. ConcepTest: For which reaction is an oxygen atom reduced and a chlorine atom oxidized? a. 2NaOCl + F2 2 NaF + Cl2+ O2b. Cl2 + 2 O2 2ClO2c. 2NaCl + O2 2 NaOCld. H2O2 + 2 NaCl Cl2 + 2 NaOHe. None of thesei. Answer: B (Cl goes from O to +4, so it is oxidized, and O goes from 0 to -2, so it is reduced). However, C and D are also correct. 3. ConcepTest: Which chemical reaction best describes the reaction 2AgNO3 (aq) + Cu (s) 2Ag (s) + Cu(NO3)2 (aq)a. Acid-baseb. Precipitationc. Gas-formingd. Oxidation-reductioni. Answer: D1. Acid-base must make H+, make HO-, or combine H+ and HO-2. Precipitation- A+B- + C+D-3. No gas is formed4. ConcepTest: Which chemical reaction type best describes the reaction CaO (s) + H2O (I) Ca(OH)2 (s)?a. Acid-baseb. Precipitationc. Gas-formingd. Oxidation-reductioni. Answer: A (makes OH)II. Stoichiometry a. ConcepTest: For the reaction 4 NH3 + 5 O2 4 NO + 6 H2O, how many N, H, and O?i. ANSWER: 4 N, 12 H, 10 O b. ConcepTest: For the reaction aN2 + bO2 N2aO2b, if 2.8 g of N2 yields 9.2 g of N2aO2b, what are a and b, respectively?i. ANSWER: B. You used 6.4 grams of O. Nitrogen is 14, so 2(14) is 28 (a tenth of a
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