MCDB 108A Quiz 3

# MCDB 108A Quiz 3 - MCDB 108A Online Quiz#3 Duane W Sears...

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Online Quiz #3 MCDB 108A Duane W. Sears FALL 2010 9/12/2010 page 1 of 2 pages Online Quiz3.docx For Questions 1-2 and 4-11 calculate accurate numerical answers to within the specified decimal range as indicated for each question. Follow the examples in parentheses. Problem (1) Calculate the pK dn of a 0.01 M weak acid solution in pure water if pH = 4.20 after equilibrium has been achieved. NOTE : Your numerical answer should be entered to 2 decimal points and credit will be given for any answer within +/-0.05 of the best answer. ! pK dn = ______. (For example: 0.01, 2.34, 56.78, etc.) Problem (2) Calculate the decimal fraction - i.e., Yd - of 0.1 M formic acid that is dissociated in pure water at equilibrium if pK dn = 3.75 . NOTE : Your numerical answer should be entered to 3 decimal points and credit will be given for any answer within +/-0.0015 of the best answer. ! Y d = ______. (For example, 0.001, 2.305, 56.785, etc.) Problem (3) From the following possibilities, select the equation that correctly defines the fraction dissociated , or the dissociation fraction ( Yd ), for a weak acid with dissociation constant , K dn , at the equilibrium H ion concentration , [H + ] . (a) Y d = K dn / (1 + [H + ] * K dn ) (b) Y d = 1 / ([H + ] + K dn ) (c) Y d = K dn / ([H + ] + K dn ) (d) Y d = [H + ] / ([H + ] + K dn ) (e) none of these Problem (4) Calculate the dissociation fraction - i.e., Yd - for an equilibrium solution of lactic acid

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## This note was uploaded on 10/29/2010 for the course MCDB MCDB 108A taught by Professor Sears during the Fall '09 term at UCSB.

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MCDB 108A Quiz 3 - MCDB 108A Online Quiz#3 Duane W Sears...

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