Question

The equilibirum constant (k) for an amino acid acting as an acid-base pair in solution is:

AA + H_{2}O <--------> H_{3}O^{+}
+ AA^{-} k = 9.03 E -5

Calculate the absorbance at 433 nm for the solution if the
initial AA concentration of 4E-4 M, given that
*ɛ*_{AA} = 9.04 E3 M and *ɛ*_{AA-} =
0.855 E3 M

Answer #1

Here, absorbance = e * L * c

where, e = molar extinction coefficient

L = path length of the cell holder

c = concentration of the solution

=> absorbance = 9.03 *
10^{-5} * 433 * 10^{-9} * 4 * 10^{-4}

= 1.564 * 10^{-14}

A solution of a weak acid HA has initial concentration c and
acid ionization constant Ka. To what concentration should the acid
be diluted to make [H3O+] half of what it was? Answer in terms of c
and Ka.

An acid-base indicator, HIn, dissociates according to the
following reaction in an aqueous solution. HIn---> In- + H+ .
The protonated form of the indicator, HIn, has a molar absorptivity
of 3827 M–1·cm–1 and the deprotonated form, In–, has a molar
absorptivity of 26210 M–1·cm–1 at 440 nm. The pH of a solution
containing a mixture of HIn and In– is adjusted to 5.92. The total
concentration of HIn and In– is 0.000117 M. The absorbance of this
solution was...

Find the H3O+ concentration of a 0.210 M hypochlorous acid
solution (whose acid dissociation constant is Ka=2.9×10−8).

The acid-dissociation constant for benzoic acid (C6H5COOH) is
6.3×10−5.
Part A
Calculate the equilibrium concentration of H3O+ in the solution
if the initial concentration of C6H5COOH is 6.6×10−2 M
.
Express your answer using two significant figures.
[H3O+] =
M
SubmitRequest Answer
Part B
Calculate the equilibrium concentration of C6H5COO− in the
solution if the initial concentration of C6H5COOH is
6.6×10−2 M .
Express your answer using two significant figures.
[C6H5COO−] =
M
SubmitRequest Answer
Part C
Calculate the equilibrium...

The acid-dissociation constant for benzoic acid (C6H5COOH) is
6.3×10−5.
Part A Calculate the equilibrium concentration of H3O+ in the
solution if the initial concentration of C6H5COOH is 6.3×10−2 M .
Express your answer using two significant figures.
Part B Calculate the equilibrium concentration of C6H5COO− in
the solution if the initial concentration of C6H5COOH is 6.3×10−2 M
.
Part C Calculate the equilibrium concentration of C6H5COOH in
the solution if the initial concentration of C6H5COOH is 6.3×10−2 M
. Express...

The acid-dissociation constant for benzoic acid (C6H5COOH) is
6.3×10−5. Part A Calculate the equilibrium concentration of H3O+ in
the solution if the initial concentration of C6H5COOH is 6.3×10−2 M
. Express your answer using two significant figures. Part B
Calculate the equilibrium concentration of C6H5COO− in the solution
if the initial concentration of C6H5COOH is 6.3×10−2 M . Part C
Calculate the equilibrium concentration of C6H5COOH in the solution
if the initial concentration of C6H5COOH is 6.3×10−2 M . Express...

The acid-dissociation constant for benzoic acid ( C 6 H 5 COOH)
is 6.3× 10 −5 .
Part A Calculate the equilibrium concentration of H3O+ in the
solution if the initial concentration of C6H5COOH is 5.7×10−2 M .
Express your answer using two significant figures.
Part B Calculate the equilibrium concentration of C6H5COO− in
the solution if the initial concentration of C6H5COOH is 5.7×10−2 M
. Express your answer using two significant figures.
Part C Calculate the equilibrium concentration of...

The following equilibrium is established when 0.0120 M benzoic
acid (C 6H 5COOH) is dissolved in water. C 6H 5COOH + H 2O ⇌ C 6H
5COO - + H 3O + K a = 6.3 x 10 -5 Which statement is false? a.
Hydroxide ion concentration is negligible with respect to hydrogen
ion concentration. b. C6H5COOH is a weak acid. c. H2O is a weak
base. d. C6H5COO- is the conjugate acid of benzoic acid. e. H3O+ is
the...

The degree to which a weak base dissociates is given by the
base-ionization constant, Kb. For the generic
weak base, B
B(aq)+H2O(l)⇌BH+(aq)+OH−(aq)
this constant is given by
Kb=[BH+][OH−]/[B]
Strong bases will have a higher Kb value. Similarly,
strong bases will have a higher percent ionization
value.
Percent ionization=[OH−] equilibrium/[B] initial×100%
Strong bases, for which Kb is very large, ionize
completely (100%). For weak bases, the percent ionization changes
with concentration. The more dilute the solution, the greater the
percent ionization....

Learning Goal:
To understand the relation between the strength of an acid or a
base and its pKa and pKb values.
The degree to which a weak acid dissociates in solution is given
by its acid-ionization constant, Ka. For the
generic weak acid, HA,
HA(aq)⇌A−(aq)+H+(aq)
and the acid-ionization constant is given by
Ka=[A−][H+][HA]
Similarly, the degree to which a weak base reacts with H2O in
solution is given by its base-ionization constant,
Kb. For the generic weak base, B,
B(aq)+H2O(l)⇌BH+(aq)+OH−(aq)...

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