experiment #10.docx - Purpose: The purpose of experiment...

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Purpose:The purpose of experiment number 10 is to determine the molar mass and aciddissociation constant of acetic acid (a weak monoprotic acid) by titration and pHmeasurement of solutions containing known concentration of acetic acid. We willalso determine the molar mass and acid dissociation constant of an unknown weakacid and learn how a pH meter works and how to measure the pH of a solution.Introduction:Acetic acid ionizes according to the reaction1
(1) HA + H2OH3O++A-Ha represents acetic acid (or any generic weak monoprotic acid) and A-representsacetate ion, CH3CO2The equilibrium constant expression is given by(2) Ka= [H3O+][A-]/[HA]In order to determine Ka,all that remains is to calculate the [H3O+] from themeasured pH(3) pH = -log [H3O+][H3O+]= 10-pH(4) PKa= -log (Ka);Ka= 10-pKa(5) Molar mass = g HA/L X L HA/mol HA = g HA/ molTo see how we can determine the stoichiometric concentrations of HA and A-(6) HA + Na++ OH-Na++A-+ H2O(7) Mol Na+A-formed= mol NAOHadded(8) Mol HAfinal= mol HAoriginal

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Term
Fall
Professor
SHAIR
Tags
pH, g L acetic acid

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