Chemistry 1N Data Analysis: Determining Equilibrium Constants and Reaction Rates - Prof. R, Assignments of Chemistry

Download Chemistry 1N Data Analysis: Determining Equilibrium Constants and Reaction Rates - Prof. R and more Assignments Chemistry in PDF only on Docsity! Chemistry 1N Data Analysis Problems Name_______________________________ Section______________TA_____________ Show all work. Report values with proper number of significant figures. 1. A student determines the equilibrium constant, K, at 25oC. 1a.S/he performs three measurements. Find the average value of K, K. Find the standard deviation in K, K. 1b.S/he performs a fourth trial and finds a K value of 727. Find the new average value of K, K. Find the new standard deviation in K, K. 1c.Should the student use trial 4 (circle one)? Yes / No Why or why not? 2. Reaction rates can be experimentally challenging to measure, and the data analysis requires care. A student wishes to determine the rate of a reaction: 2A- → A2. The rate depends on the concentration of A-, as well as other factors such as temperature. The rate law, which allows the rate to be determined for any concentration of A-, is of the form: The following must be determined by experiment: m, the order of reaction with respect to A-; and, k, the rate constant at a given temperature. Solutions of A- are prepared by mixing a more concentrated A- solution with water (solvent). 2a.Calculate the concentration of A2- in each diluted solution. Show an example calculation. Trial K 1 413 2 447 3 385 Trial K 1 413 2 447 3 385 4 727 Trial # mL 0.10M A- mL water Molarity of A-dil 1 1.0 12.0 2 2.0 11.0 3 3.0 10.0 4 4.0 9.0 5 5.0 8.0 ]k[A = Rate m 2b. The reaction rate is measured for each solution by determining the change in concentration of A2 in a given time: ΔAA2/ΔAt = (A2,t – A2,0)/(tt – t0). Given the following data, calculate the rate of reaction in each trial. Show an example calculation. Trial # Time (s) A2 formed M(mol/L ) Rate (M/s) 1 760 0.0019 2 370 0.0038 3 256 0.0058 4 180 0.0077 5 150 0.0096 2c.Take the log of the rate law expression. Rearrange the resulting equation so that it is linear in form: y = (slope)x + intercept, with log[A-] as x, log(rate) as y, and the reaction order m as the slope. 2d.Using the linear equation you wrote in 2c, graphically determine m. Put log(rate) on the y-axis and log[A-]on the x-axis. Make the scale appropriate for your data. Show example calculations. log[A-] log(rate) ]k[A = Rate m