Question

In: Chemistry

Calculate [H3O + ] for a 2.5 x 10-4 M solution of weak acid (Ka =...

Calculate [H3O + ] for a 2.5 x 10-4 M solution of weak acid (Ka = 5.3 x 10-4 )

A.
1.4 x 10^-4 M
B.
2.1 x 10^-4 M
C.
6.2 x 10^-4 M
D.
7.3 x 10^-4 M
E.
1.9 x 10^-4 M

Expert Solution

Let us represent weak acid as HA. Its dissociation is as shown below:

The equilibrium constant

The initial concentration of HA is .
Let x M be the change in the concentration of HA to reach equilibrium.
Prepare an ICE table.


Initial concentration (M)	0	0
Change in concentration (M)
Equilibrium concentration (M)

Substitute values in the equilibrium constant expression

This is quadratic equation with solution

The negative value is discarded as concentration cannot be negative.

Hence,

Hence, option E is the correct answer.

Note: One can also calculate the pH as shown below:

queen_honey_blossom answered 1 year ago

formic acid is a weak acid Ka= 1.9 x 10^-4 . Calculate the ph of a...

formic acid is a weak acid Ka= 1.9 x 10^-4 . Calculate the ph of a .50M solution of formic acid. what is the degree of ionization?

Calculate: a) Ka and pKa of a 0.010M solution of a weak acid that is 4%...

Calculate: a) Ka and pKa of a 0.010M solution of a weak acid that is 4% ionized. b) Kb and pKb of a 0.010M solution of a weak base whose pH = 10.10. Please show all steps.

The weak acid HZ has a Ka of 2.55 x 10-4. Calculate the pH of a...

The weak acid HZ has a Ka of 2.55 x 10-4. Calculate the pH of a 0.235 M solution.

Chloropropionic acid, ClCH2CH2COOH is a weak monoprotic acid with Ka = 7.94 x 10-5 M. Calculate...

Chloropropionic acid, ClCH2CH2COOH is a weak monoprotic acid with Ka = 7.94 x 10-5 M. Calculate the pH at the equivalence point in a titration 34.8 mL of 1.09 M chloropropionic acid with 0.2 M KOH.

Chloropropionic acid, ClCH2CH2COOH is a weak monoprotic acid with Ka= 7.94 x 10-5 M. Calculate the...

Chloropropionic acid, ClCH2CH2COOH is a weak monoprotic acid with Ka= 7.94 x 10-5 M. Calculate the pH at the equivalence point in a titration 24.1 mL of 1.33 M chloropropionic acid with 0.3 M KOH.

If a buffer solution is 0.400 M in a weak acid (Ka = 6.7 × 10-6)...

If a buffer solution is 0.400 M in a weak acid (Ka = 6.7 × 10-6) and 0.290 M in its conjugate base, what is the pH? ------------------------ What is the pH of 75.0 mL of a solution that is 0.041 M in weak base and 0.059 M in the conjugate weak acid (Ka = 7.2 × 10–8)?

If a buffer solution is 0.160 M in a weak acid (Ka = 1.0 × 10-5)...

If a buffer solution is 0.160 M in a weak acid (Ka = 1.0 × 10-5) and 0.470 M in its conjugate base, what is the pH?

Calculate the pH of a 0.587 M aqueous solution of phenol (a weak acid) (C6H5OH, Ka...

Calculate the pH of a 0.587 M aqueous solution of phenol (a weak acid) (C6H5OH, Ka = 1.0×10-10) and the equilibrium concentrations of the weak acid and its conjugate base Calculate the pH of a 0.0183 M aqueous solution of acetylsalicylic acid (HC9H7O4, Ka = 3.4×10-4) and the equilibrium concentrations of the weak acid and its conjugate base

A 100 mL solution of 0.100 M hydroxyacetic acid (Ka = 1.48 x 10-4 ) is...

A 100 mL solution of 0.100 M hydroxyacetic acid (Ka = 1.48 x 10-4 ) is titrated with 0.0500 M KOH. Answer the questions that follow; (a) What volume of KOH is required to reach the equivalence point? (b) What is the pH at the equivalence point? (c) Which indicator below would be suitable for determining the end point? Methyl yellow (pKa 3.1), chlorophenol red (pKa 6.2), thymol blue (pKa 8.9)

Lactic acid (HC3H5O3), a weak monoprotic acid with a Ka = 1.4 x 10-4, is titrated...

Lactic acid (HC3H5O3), a weak monoprotic acid with a Ka = 1.4 x 10-4, is titrated with KOH. If you have 50.0 mL of a 0.500 M HC3H5O3solution, calculate the pH after 150.0 mL of 0.250 M KOH have been added: