Question

A 0.250 M solution of a weak base has a pH of 9.30. What is the base hydrolysis constant, Kb, for the weak base?

Answer #1

from pH find the pOH

pH + pOH = 14

pOH = 14 - pH = 14 - 9.30 = 4.7

[OH-] = 10^-pOH = 10^-4.7 = 2 x 10^-5 M

let us week base is called B

construct ICE table

B (aq) + H2O (l) <-----> BH (aq) + OH- (aq)

I 0.25 0 0

C -x +x +x

E 0.25-x +x +x

but we have alredy concentration of OH- = x = 2 x 10^-5 M

if 1 mol of B hydrolyse will give 1 mol of BH and 1 mole of OH_

so concentration of [OH-] = [BH] = 2 x 10^-5

concentration of [B] = 0.25 - x = 0.25 - 2 x 10^-5 = 0.24998 M

now expression for Kb is

Kb = [OH-] [BH] / [B]

Kb = [2 x 10^-5 ] [2 x 10^-5 ] / [0.24998]

Kb = 1.6 x 10^-9

A 0.300 M solution of a weak base has a pH of 9.10. What is the
base hydrolysis constant, Kb, for the weak base?

A 0.500 M solution of a weak base has a pH of 9.20. What is the
base hydrolysis constant, Kb, for the weak base?

A 0.100 M solution of a weak base has a pH of 9.75. What is the
base hydrolysis constant, Kb, for the weak base?

The pH of a 0.032 M solution of a weak base is 9.83. What is the
pKb for this base? That is the -log(Kb).

A 0.0100 M solution of a weak base has pH = 9.78 at T = 25 C.
What is the numerical value for Kb for the weak base?

A 0.120 M solution of a weak base has a pH of
11.27.
Part A
Determine Kb for the base.

A 1.70 M solution of a weak base has a pH of 9.7. Calculate the
Kb.

A 1.70 M solution of a weak base has a pH of 9.7. Calculate the
Kb.

A 0.0884 M solution of a weak base has a pH of 11.79. What is
the identity of the weak base? Weak Base Kb Ethylamine (CH3CH2NH2)
4.7 X 10–4 Hydrazine (N2H4) 1.7 X 10–6 Hydroxylamine (NH2OH) 1.1 X
10–8 Pyridine (C5H5N) 1.4 X 10–9 Aniline (C6H5NH2) 4.2 X 10–10

A 0.150 M solution of a weak base has a pH of 11.28. Determine
the Kb for the base. Express your answer using two significant
figures.

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 17 minutes ago

asked 33 minutes ago

asked 50 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago

asked 3 hours ago

asked 3 hours ago

asked 3 hours ago

asked 3 hours ago