General Chemistry Lecture 102a In class notes for September 26, 2007 OWL Chapter 4 Acid/Base due 9/27 Redox problems extended to Monday. Exam 1 regrade request due next Monday. Last time Anhydrides Acid/base neutralizations Redox demo (Ag tree, SO3) Today Periodcity and oxides Titrations <a href="/keyword/redox-reactions/" ><a href="/keyword/redox-reaction/" >redox reaction</a> s</a> Neutralizations See A Periodic trends (figure 4.8) These elements are usually found in the form X-O-H Bases X+ O- - H There is a large electronegativity difference between X and O Acids X O- + H+ Because of the electronegativity between the center atom and the hydrogens Periodic trends can predict what will react Metals will give us base anhydrides Nonmetals usually give acid anhydrides Acid/ Base Titrations (really Chapter 2) See B The endpoint When the indicator turns color The equivalence point is when the moles of acid are equal to the mole of base See C This is used for 1:1 stoichiometry between the acid and the base When it is not 1:1, See D Do not apply simple 1:1 equation when it is not 1:1! Oxidation Reduction Reactions (electron transfer) Oxidation # s change See E Two ways to follow electrons First way is to follow formal charge Electrons shared ( covalent ) See F Oxidation number assumes ( ionic behavior ) and the most electronegative atom gets the electrons See G Oxidation numbers work best for ionic compounds See page 170 of Oxtoby (rules of oxidation numbers) General Chemistry Lecture 102a In class notes for September 26, 2007 See H Be able to identify a <a href="/keyword/redox-reaction/" >redox reaction</a> . What is oxidized? Historically it was whenever oxygen was added to a compound Now we consider oxidation a more general reaction, it occurs when something loses electrons When it gains electrons, it is called reduction Be able to know what is oxidized and what is reduced during the reaction.