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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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figureskater figureskater
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11 years ago
weight is 112. Adding 1.12 grams to 100ml of water, you measure the pH at 4.57. What is the pKa?
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11 years ago
moles acid = 1.12 g / 112 g/mol=0.01
initial concentration acid = 0.01 mol/ 0.100 L = 0.1 M

HA Leftwards Arrow---> H+ + A-

at equilibrium : [H+]= [A-]= 10^-4.57 =2.69 x 10^-5 M

Ka = [H+][A-]/ [HA] = ( 2.69 x 10^-5)(2.69 x 10^-5) / 0.1 - 2.69 x 10^-5 =7.24 x 10^- 9

pKa = 8.14
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fightingquakerfightingquaker
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11 years ago
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