Consider the titration of a 23.0?mL sample of 0.110MHC2H3O2 with 0.120M NaOH. De

ID: 839114 • Letter: C

Question

Consider the titration of a 23.0?mL sample of 0.110MHC2H3O2 with 0.120M NaOH. Determine each of the following.

Part A

the initial pH

Express your answer using two decimal places.

Part B

the volume of added base required to reach the equivalence point

Part C

the pH at 6.00mL of added base

Express your answer using two decimal places.

Part D

the pH at one-half of the equivalence point

Express your answer using two decimal places.

Part E

the pH at the equivalence point

Express your answer using two decimal places.

A)let the intial dissociation be x.so,

1.8*10^-5 = x^2/(0.11-x)

or x=1.398*10^-3

so pH=-log(1.398*10^-3)

=2.85

B)equating the number of moles,

23*0.11=0.12*x

or x=21.08 mL

C)pH=pKa+log(salt/acid)

=4.76 + log( 0.12*6/(23*0.11-6*0.12))

=4.36

d)pH of strong base and a weak acid at the equivalence point,

pH=7 +0.5 pKa+log(salt/acid)

=7+0.5*4.76 + log((23*0.11)/(23+21.08))

=8.14

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