CHM 116 1st Edition Lecture 2 Outline of Last Lecture I. Units of ConcentrationA. Equations for molarity, molality, mole fractionOutline of Current Lecture II. QuestionsIII. GoalsIV. DemonstrationV. Reaction RatesB. Ludwig WilhelmyCurrent LectureII. Questions- Will chemical reaction produce desired products?- If so, are products produced in useful quantities?- How rapidly will the chemical reaction occur?III. Goals- Quantify rates of chemical reactions- Understand factors that influence rates of chemical reactions- Determine “reaction mechanism”IV. Demonstration- 2H2O2 (aq) 2H2O (l) + O2 (g)A. Hydrogen peroxide (30%)B. When soap was added to the peroxide, there were not very many bubbles formedC. When potassium iodide was added, a ton of yellow foam was produced Catalyst- immensely sped up the reaction- 2MnO4- (aq) + 5H2C2O4 (aq) + 6H3O+ (aq) 2Mn+2(aq) + 10CO2 (g) + 14H2O (l)o The MnO4 is purple and all the other solutions are colorlessThese 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.o When the reagents were added to hot water, the reaction took place veryquickly and became clearo When the reagents were added to MnCl2, the reaction occurred faster than when they were added to a solution of NaClo Temperature, concentration, and catalysts are three things that affect reaction rateV. Reaction Rates- Rate= Change in moles of A/change in time = dnA/dt where A is any reactant or product- Rate = d[A]/dt at constant volumeB. 1850- Ludwig Wilhelmyo H2O + C12H22O11 (sucrose) H30+ C6H12O6 (glucose) + C6H12O6 (fructose) Rate= -d[sucrose]/dt directly proportional to [sucrose][H3O+] Rate= k[sucrose][H3O+] Value of k changes as temperature changes This is now known as the rate law, which was originally discovered by Wilhelmy- In general, Rate= k[A]x[B]y[C]z…o [A]… are the molar concentrations of reactants A, B, Co The “exponents” x, y, z are the “orders” of each reactant Orders rely on experimental data- 2H2O2 (aq) 2H2O (l) + O2 (g)o If you were to make a bunch of hydrogen peroxide (3%), bottle it up and ship it in a truck in the middle of summer, you would need to know if it will be hot enough to explode the bottleso This is one way that reaction rates are used in “real
View Full Document