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lecture 10 - Turn on Camptasia Recording No Class Wednesday...

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Unformatted text preview: Turn on Camptasia Recording! No Class Wednesday Feb 20th EXAM WED Feb 20th 131 Markus at 7 pm due to EXAM Make-up exam During Class time Feb 20th in this room. oo ... 1 SI Sessions Wednesday Feb 20th NONE Due to Exam Review Sessions Tuesday Feb 19th 5:30 pm (Hardy) GOESSMAN 51 Tuesday Feb 19th 8:30-9:45 pm (Tami) Library Room 1049 ... 2 Osmosis at the Particulate Level ... 3 Osmotic Pressure, Equilibrium is reached when pressure produced by extra solution counterbalances pressure of solvent molecules moving through the membrane. OSMOTIC PRESSURE, Osmotic pressure ... 4 Osmosis Osmosis of solvent from one solution to another can continue until the solutions are they have the same concentration. ISOTONIC -- ... 5 Osmosis and Living Cells No water in or out Water goes out of cell ... Water goes into cell 6 Reverse Osmosis: Water Desalination Water desalination plant in Tampa ... 7 Osmosis : Calculating a Molar Mass Dissolve 35.0 g of hemoglobin in enough water to make 1.00 L of solution. measured to be 10.0 mm Hg at 25 C. Calc. molar mass of hemoglobin. hemoglobin. ... 8 Chemical Kinetics Thermodynamics tells us if a reaction is product- or reactant-favored. Thermodynamics gives us no info on how fast reaction goes from reactants to products. Kinetics is the study of reaction rates and their mechanisms (the way the reaction proceeds). ... 9 Reaction Rates Reaction rate = change in concentration of a reactant or product with time Rate units = concentration / time Types of rates initial rate t a ate average rate instantaneous rate ... 10 Determining a Reaction Rate Blue dye is oxidized with bleach. The rate (the change in dye concentration with time) can be determined from the plot. Time ... 11 Following reaction progress For the reaction 2N2O5 --> 4NO2 + O2 we can follow the progress by monitoring: the rate of formation of NO2 the rate of formation of O2 , and/or the rate of disappearance of N2O5 Dye Conc c ... 12 Determining an Instantaneous Reaction Rate ... 13 Determining an Average Reaction Rate ... 14 Determining an Reaction Rate for a Period of Time ... 15 Factors Affecting Rates 1. Concentrations (Mg in H202) 2. Physical state of reactants and products (eg. Lycopodium powder) 3. Temperature (hot bleach) 4. Catalysts (potato 4 C t l t ( t t & H2O2) (MnO2 & H2O2) ... 16 Concentrations and Rates To determine a reaction s reaction's mechanism, we study the reaction's rate and concentration dependence ... 17 Concentrations and Rates Take reaction where Cl- in cisplatin [Pt(NH3)2Cl2] is replaced by H2O ... 18 Concentrations & Rates Rate of change of conc of Pt compd = Am' t of cisplatin reacting ( o / ) o c sp a eac g (mol/L) elapsed time (t) Rate of reaction is proportional to [Pt(NH3)2Cl2] p We express this as a RATE LAW where k = rate constant k is independent of conc. but increases with T ... 19 Concentrations, Rates, & Rate Laws In general, for The exponents m, and n are the reaction order can be 0, 1, 2 or fractions b 0 1 f i must be determined by experiment Not necessarily the coefficients for the reaction ... 20 Interpreting Rate Laws Rate = k [A]m[B]n If m = 1, rxn. is 1st order in A If [A] doubles, then rate goes up by factor of __ If m = 2, rxn. is 2nd order in A. Doubling [A] increases rate by ________ g y If m = 0, rxn. is zero order. If [A] doubles, rate ________ ... 21 Deriving Rate Laws Example: Derive the rate law and k for CH3CHO(g) --> CH4(g) + CO(g) from experimental data for rate of disappearance of CH3CHO Expt. 1 2 3 4 [CH3CHO] (mol/L) 0.10 0.20 0.30 0.40 ... Rate of disappearance of CH3CHO (mol/Lsec) 0.020 0.081 0.182 0.318 22 Deriving Rate Laws Rate of rxn = k [CH3CHO]2 Here the rate goes up by ______ when initial conc. doubles. Therefore, we say this reaction is _________________ order. Now determine the value of k. Use expt. #3 data-- data-- Using k you can calc. rate at other values of [CH3CHO] at same T. ... 23 Below is a zero order reaction for the decomposition of Ammonia. What is the rate law? 2NH3(g) --> N2(g) +3 H2 (g) A. B. C. D. Rate = k [NH3]2 Rate = k [NH3]2 [H2]3 Rate = k [N2] [H2]3 Rate = k ... 24 Based on this data, what order is this reaction in NO? 2NO(g) + Cl2(g) --> 2NOCl(g) A. B. C. D. Zero First Second Third ... 25 Based on this data, what order is this reaction in Cl2? 2NO(g) + Cl2(g) --> 2NOCl(g) A. B. C. D. Zero First Second Third ... 26 What is the rate law for this reaction? 2NO(g) + Cl2(g) --> 2NOCl(g) A. B. C. D. Rate = k [NO]2 Rate = k [NO]2 [H2]1 Rate = k [NO]2 [Cl2] Rate = k [NOCl]2 ... 27 Reaction Rate Constants Zero order reaction: k are mol/L time First order reaction: k are time-1 Second order reaction: k are L/mol time ... 28 CO(g) + NO2(g) --> CO2(g)+ NO2(g) The initial rate of the reaction above was measured at 25C for various initial concentrations of CO and NO2. Determine the rate equation, the rate constant and the units of the rate constant. ... 29 ...
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