TASK DESCRIPTION Prepare a written information report, using secondary sources for research, on the following: - the processes of dissociation of a range ionic substances and acids and bases. - the use of the equilibrium constant, Keq, for reactions involving, but not limited to: - the dissociation of ionic substances and - the dissocation of acids and bases. Then use your knowledge and findings from your report to - place the attached list of acids in order of strength. - complete the attached worksheet to determine the equilibrium constant for the reaction CH3COOH(aq) + CH30H(aq) CH3COOCH3(aq) + H20(l) OUTCOMES TO ASSESSED A Student: BE CH12-3 conducts investigations to collect valid and reliable primary and secondary data and information. CH12-4 selects and processes appropriate qualitative and quantitative data and information using a range of appropriate media. CH12-5 analyses and evaluates primary and secondary data and information. CH12-6 solves scientific problems using primary and secondary data, critical thinking skills and scientific processes. CH12-7 communicates scientific understanding using suitable language and terminology for a specific audience or purpose. CH12-12 explains the characteristic of equilibrium systems, and the factors that affect these systems. MARKING CRITERIA Responses will be assessed on how well they demonstrate: knowledge and understanding of the dissociation of ionic substances and acids and bases. knowledge and understanding of equilibrium constants. ' skills in analysing and presenting data. MARKING GUIDELINES Extensive description of the ranges of dissociation of ionic substances and acids and bases with named examples. Description of the methods for calculating the equilibrium constants for ionic substances and acids and bases, with named examples. Extensive analysis of the use of equilibrium constants for reactions involving a range of identified ionic substances and acids and bases. Correct ranking of acids in terms of strength. Clear, accurate graphs used in determining equilibrium position and concentrations. Correct use of stoichiometric relationships and concentrations to calculate the equilibrium constant for the reaction between methanol and ethanoic acid. Thorough description of the ranges of dissociation of ionic substances and acids and bases with examples. Description of the methods for calculating the equilibrium constants for ionic substances and acids and bases with examples. Thorough description of the use of equilibrium constants for reactions involving a range of ionic substances and acids and bases. Correct ranking of acids in terms of strength. Clear, accurate graphs used in determining equilibrium position and concentrations. Correct use of stoichiometric relationships and concentrations to calculate the equilibrium constant for the reaction between methanol and ethanoic acid. Sound description of the dissociation of ionic substances and acids and bases with examples. Description of the methods for calculating the equilibrium constants for ionic substances and acids and bases. Sound description of the use of equilibrium constants for reactions involving ionic substances and acids and bases. Correct ranking of acids in terms of strength. Clear graphs used in determining equilibrium position and concentrations. Correct use of stoichiometric relationships and concentrations to calculate an equilibrium constant for the reaction between methanol and ethanoic acid. 25-30 19-24 13-18 c Basic outline of the dissociation of ionic substances and acids and bases. Outline of the methods for calculating the equilibrium constants for ionic substances and acids and bases. Outline of the use of equilibrium constants for reactions involving a range of ionic substances and acids and bases. Correct ranking for most acids in terms of strength. Graphs used to attempt determination of the equilibrium position and concentrations. Correct use of stoichiometric relationships, some correct concentrations for the reaction between methanol and ethanoic acid and attempt at the equilibrium constant. Identification that ionic substances and acids and bases dissociate in water. Generic formula to calculate the equilibrium constant given. Equilibrium constants for the dissociation of some ionic substances and acids and bases stated. Attempt at ranking acids in order of strength. Graphs drawn. Incorrect use of stoichiometric relationships, incorrect concentrations of s ecies. No e uilibrium constant calculation. 7-12 D 1-6 $ nelsonnet——-—Name: Class: ACTIVITY SHEET Activity sheet 3.3 Ethanoic acid and methanol in aqueous solution Ethanoic acid and methanol in aqueous solution react rather slowly to form methyl acetate, reaching an equilibrium condition represented by the balanced chemical equation: CH3COOH(aq) + CH30H(aq) CH3COOCH3 (aq) + H20(1) ethanoic acid ethanol methyl acetate Methyl acetate belongs to a class of compounds called esters, formed by the reaction between carboxylic acids and alcohols. This reaction, and corresponding ones to form other esters, is called esterification. 'Ihe reaction is catalysed by small amounts of sulfuric acid in solution. At any given time during the reaction, a sample can be taken from a reaction and the amount of ethanoic acid in the sample can be measured by titration with a standard sodium hydroxide solution - making a correction for the amount of sodium hydroxide solution that reacts with the sulfuric acid present. When a reaction mixture is made in which the concentration of ethanoic acid is 1.00 mol la-I , the concentration of ethanol is 1.10 mol El, and the solution is at 25 0C, a typical set of measurements of the ethanoic acid concentration at various times is listed here. O Cengage Learning Australia Pty Ltd 2018 WS3.3 ethanoic acids and methanol in aqueous solution_fc www.nelsonnet.com.au 10 20 30 40 50 75 100 150 0.1 4 0.1 200 250 0 0.0 9 0.0 enelsonnet 9 1 On a graph, with concentration on the vertical axis ranging from O to 1.10 mol V I , and time ranging from 0 to 250 s on the horizontal axis, plot the changing ethanoic acid concentration. O Cengage Learning Australia Pty Ltd 2018 WS3.3 ethanoic acids and methanol in aqueous solution_fc www.nelsonnet.com.au 2 Why do you think that more frequent measurements are taken early in the reaction than later? 3 Use the balanced chemical equation for the reaction to deduce the concentration of ethanol in each of the samples taken for ethanoic acid estimation. On the graph, plot the change of ethanol concentration over time. e nelsonnet 4 Deduce the concentration of methyl acetate in each of the samples taken for ethanoic acid estimation and plot the change of its concentration over time. 5 At approximately what time did the reaction mixture come to chemical equilibrium? O Cengage Learning Australia Pty Ltd 2018 WS3.3 ethanoic acids and methanol in aqueous solution_fc www.nelsonnet.com.au 6 Estimate the equilibrium constant for the reaction at 250C. 7 Was there any reaction occurring at t= 250 s? O Cengage Learning Australia Pty Ltd 2018 WS3.3 ethanoic acids and methanol in aqueous solution_fc www.nelsonnet.com.au Parkes High School HSC Chemistry Assessment Task 1. Acid Stren øths. Rank the following acids from strongest (1) to weakest (10) Acid Nitrous Acid Nitric Acid Hydrofluoric Acid H drochloric Acid Acetic Acid Methanoic Acid Hydrobromic Acid Hydroiodic Acid Propanoic Acid Sulfuric Acid Strength Rank