Question

I. A solution of acetylsalicylic acid, HICHO.(a wenk monoprotie weid) in Aspirin, is prepared by dissolving 18 mg into ethanol to prepare a 100 ml solution. The pl of this solution was determined to be 3.60. a Calculate the molarity of the solution. 15 points b. Calculate the acid dissociation constant, K. for the acid. 17 points) c. Calculate the Ks value for the conjugate base of acetylsalicylic acid. [3 points]

Answer 1

mass of adtylealitylic actd used 18mg 6 o0188 molaer mars o aatyl salicylic adtd leo 1588/wdl Namber d mdles aatyl Salityclic acad. mars molar mass -0.0001 mdu neimber mds aatyl salityle oO188 aad 4 180.1589lud volume the 8dution lo0 mL0-1L Molaesty ef the solution: Neumber4 mdus oo00 md 0.0olm O.IL vdlume in Litres molaaidy 4 aatyl salityhic actd sdution = 0.001M a dtyl saliyeic acd sdutian p-GCH3 3-60 pH + H+ Aatyl Salityclic Acid Aayl salicylat. equiltbeim Constant Ka Fatyl saligylab7 Crt Aatyl salicgelic Act Dissociation ph logCH cof Coot H Tnitial Grmantatiatn) chamge 0.001m Om Com m Conentiationn) Equilibeam Covicentiationry Co.01-2)m Cx) m Substitue the alove values in eguation Ka -GAatylsaligylak) CH A atyloalitycic Actal CoM M)m 1 Co-o01-m Ka O001-2M

pH Coniantiationg CH10 PH PH= 960 -3.60 Jo 4 2.511X10 m Peoton 0.0002511 m: Contontiation Prdten CH- ) Subotitue this value im eguation Ka-m (2.511X10M - 2.511X10m Co001-0)m Ka = CO001-251110m Attd dissociation onstant (ka)- g.42x10 -5 Kb value 4 tCojugat base can be calaulatad by fAlowoing frdmula Ka 4 aatyl saliaylic actd 8.49xios KaxKb Kw Kb =Kw Ka 17 O 11816 XI0 8.42x105 Kb value fur Gonjugat base 11816X10 -10