rev’d 8/20/09
Analysis of Unknown Acids by pH Titration
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Name Your name here
Lab Partners’ Names Your partners' names here
Date of Experiment
Date Report Submitted
Abstract
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The molecular weight and pKa of two unknown monoprotic acids were determined by titration with NaOH. Acetic acid was used as a control to verify the method. For acetic acid we obtained a molecular weight of and a pKa of , which agrees with the accepted values of and . Unknown X’s molecular weight and pKa were and , which leads us to identify X as . Unknown Y’s molecular weight and pKa were and ; our best guess is that it is .
Introduction
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Discuss acid-base titrations and their stoichiometry. What is the general shape of the titration of a monoprotic acid? What is the buffer equation, and when do the approximations in the buffer equation breakdown?
Experimental Method
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Describe the procedure. Be concise. Use the past tense and the passive voice. Do Not use a “sing-song” description of your procedure: “First, we did this. After that, we did this other thing. Following that we did another thing.”
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Sample Calculations
Use the equation editor! Use algebraic symbols, not words, to represent quantities. Compute molarity and molecular weight, for acetic acid, X, and Y.
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Data Analysis
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One graph containing all three titrations, all on same plot. Figure caption below the graph, single-spaced. Using the graph, order the acids by molarity and pKa. Describe how the graph lets you do this!
Table of all Class results showing end point volume and pKa for acetic acid, X, and Y (each group).
Corrections for strong acids: Explain how the pKa’s of X and Y were adjusted using the model titration spreadsheet.
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Discussion and Error Analysis
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How reliable are the data for X and Y, based on the data for acetic acid, the control?
Conclusions
Your identities of X and Y are your claims. Your warrant requires you to discuss how you arrived at the identities for X and Y. Compare your values for MW and pKa to the accepted values. Refer to your values in the tables and graphs above. What acids did you consider, and why did you reject them?
Literature Cited
Where did you get the buffer equation from? Other general information about acid-base titrations?
Where did you get the values of pKa and MW?
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