Question

The Ka of a citric acid is 1.95x10^-5 at 25 C. what is the pH of a 0.35 M aqueous solution of citric acid?

Answer #1

Lets write the citric acid as HA

Lets write the dissociation equation of HA

HA -----> H+ + A-

0.35 0 0

0.35-x x x

Ka = [H+][A-]/[HA]

Ka = x*x/(c-x)

Assuming small x approximation, that is lets assume that x can be ignored as compared to c

So, above expression becomes

Ka = x*x/(c)

so, x = sqrt (Ka*c)

x = sqrt ((1.95*10^-5)*0.35) = 2.612*10^-3

since c is much greater than x, our assumption is correct

so, x = 2.612*10^-3 M

So, [H+] = x = 2.612*10^-3 M

we have below equation to be used:

pH = -log [H+]

= -log (2.612*10^-3)

= 2.58

Answer: 2.58

What is the pH of a 0.350 M solution of lithium citrate? (Ka
Citric Acid = 7.4 x 10-4)

Citric acid is a triprotic acidwith Ka values of 7.4 x 10-4, 1.7
x 10-5, and 4.0 x 10-7 for the first, second, and third ionization
constants, respectively. A 0.500 M solution of a monoprotic acid
with a Ka value of 7.4 x 10-4 has a pH = 1.72. What is the pH of a
0.500 M citric acid solution?

The Ka of propanoic acid (C2H5COOH) is 1.34×10−5. Calculate the
pH of the solution and the concentrations of C2H5COOH and C2H5COO−
in a 0.331 M propanoic acid solution at equilibrium.
pH=
C2H5COOH]=
[C2H5COO−]=
At 25 °C,25 °C, how many dissociated H+H+ ions are there in 357
mL357 mL of an aqueous solution whose pH is 11.95?

The Ka of hydrazoic acid (HN3) is 1.9 x 10-5 at 25.0 °C. What is
the pH of a 0.40 M aqueous solution of HN3?

What is the pH of a 0.25 M aqueous solution of KCHO2 at
25°C?
The Ka of HCHO2 is1.8 x 10-4 at 25°C.

Find the pH of a 0.380 M aqueous benzoic acid solution. For
benzoic acid, Ka=6.5⋅10−5.

What is the percent dissociation of citric acid if the solution
has a pH=3.17 an a Ka=4.0x10^-6

The Ka for acetic acid drops from
1.76x10-5 at 25°C to 1.63x10-5 at 50°C.
Between the same two temperatures, Kw increases from
1.00x10-14 to 5.47x10-14. At 50°C the density
of a .10M solution of acetic acid is 98.81% of its density at 25°C.
Will the pH of a .10 M solution of acetic acid in water increase,
decrease, or remain the same as the solution is heated from 25°C to
50°C?

a. Calculate the pH of a 0.538 M aqueous
solution of hydrofluoric acid
(HF, Ka =
7.2×10-4).
b. Calculate the pH of a 0.0242 M aqueous
solution of nitrous acid
(HNO2, Ka =
4.5×10-4).

Calculate the pH at 25° C of a 0.055 M solution of a weak acid
that has Ka = 1.4 × 10−5.

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