Our Goal Is To Complete Rate Law For The Reaction: 1 Bro3- + 5Br- + 6H+ 3 Br2 + 3H2O

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All links should be accessible in the directions attached. https://docs.google.com/spreadsheets/d/1J-PpP2nL-jgl5gtTPN-JcFtZ1qpcpcVCONT8b_B1-Hk/edit#gid=0 Spreadsheet link, should be able to edit.

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06 - Bromate Kinetics ONLINE v 20/sp Our goal is to complete rate law for the reaction: 1 BrO3- + 5Br- + 6H+ 3 Br2 + 3H2O You are going to have to do some thinking to figure out what you need to calculate, but your instructor has built a tool for your experiment, one that will give you data. Theory -To get the complete rate law, we will need to know orders of reaction of each reactant and the rate constant, k. -To calculate k, you need the rate law, take one run of the reaction and it’s rate, plug in initial concentrations of reactants, multiply by orders of reactants and calculate k at that temperature. No problem. But how do we get the orders of reaction? -To get the order of a specific reactant, we use the method of initial rates. All we need is to run the reaction with a set of initial concentrations, determine the rate of reaction. Then, change the one reactant concentration, measure the rate again and compare. Child’s play. But how do we determine rate of reaction? -To determine the rate of any reaction, the concentration of one of the substances (makes no difference which, since we have the balanced chemical equation) must be monitored over time. In this ‘experiment’, we will add together various volumes of the reactants (all with effectively no color) at a certain temperature, then measure the absorbance of the solution over time. Since Br2 is a reddish color, and has a molar absorptivity at 425 nm of 160 L/mol cm, we can calculate the concentration of Br2 at any time, using Beer’s Law. The slope of a concentration of Br2 versus time will be (by definition) rate of reaction. In previous experiments in General Chemistry, you reacted a prescribed amount of a prescribed concentration of substance A with a prescribed amount of a prescribed concentration of substance B and something happened. Those concentrations and amounts are NOT arbitrary, they can vary. Normally, your instructor does that ‘work’ for you ahead of class and you just follow their instructions. Today that ends <insert evil laugh> but as a college student, you like freedom, so it’s all ok. To do this experiment, you need to know Beer’s law and how a spectrometer works, since the data you are being given is that from such a spectrometer. Here is a short video that explains the jist of it. The tool you will be using a ‘data creator’ (see picture) You have the freedom to change lots of things. The top set are the concentrations of source solutions which must remain constant when you are taking real data. The next set of variables are parameters for one ‘run’ of the experiment. Once you have values in the yellow data cells, output data will appear in the bottom. That data is what you WOULD get if you mixed the amounts you gave up top, and started measuring the absorbance of the solution at the moment of mixing. The Abs at time 0 will always be 0, since at time 0 there is no Br2. As time goes on, Br2 appears, Abs goes up. A ‘good run’ is one where the absorbance after 15 sec is between 0.3 and 0.99. Volumes of added solutions must be between 2 and 50 mL. Stock concentrations must be between 0.1M and 2.5M. Now of course, we are using the method of initial rates here and so we need to know the initial concentrations of all the reactants. Those concentrations are NOT the concentrations of the stock solutions, https://www.youtube.com/watch?v=zuUvQN8KXOk https://docs.google.com/spreadsheets/d/1kJf-3EPd704dW677AIZ5XMULHpavkvBXGWL3W6XVhOw/edit?usp=sharing because when we add the solutions together, they immediately ‘dilute’ each other just by adding them together. To get the initial concentration you will have to use the dilution formula. Note: Molar absorptivity (epison ) of Br2 at 425 nm is 160 M/cm. The path length is 1.0 cm Note: To copy values of a cell, NOT a formula, it is a paste-special click Here is a 20 min video explaining the lab, what you’re doing and how to use the tool Lab Write Up: You will produce a full lab report that includes purpose, summary, procedure, (final) results spreadsheet, and postlab questions (which requires you to pretend you are actually doing a wetlab, not a simulation) https://www.youtube.com/watch?v=RlhISTP1lHY https://youtu.be/uBw5lpJ1r3Q https://docs.google.com/document/d/e/2PACX-1vRnOzSsQwHarXF-6n4x6Ft2t3mLQFQvIZ9o9ZS5oUS7TnFb8wJ2f86Vmx0TuumeFGz1ZNbLnla7vS_m/pub
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