Question

A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3. Determine the pH of the solution after the addition of 100.0 mL of HNO3. The Kb of NH3 is 1.8 × 10^-5.

Answer #1

Given:

M(HNO3) = 0.1 M

V(HNO3) = 100 mL

M(NH3) = 0.1 M

V(NH3) = 100 mL

mol(HNO3) = M(HNO3) * V(HNO3)

mol(HNO3) = 0.1 M * 100 mL = 10 mmol

mol(NH3) = M(NH3) * V(NH3)

mol(NH3) = 0.1 M * 100 mL = 10 mmol

We have:

mol(HNO3) = 10 mmol

mol(NH3) = 10 mmol

10 mmol of both will react to form NH4+ and H2O

NH4+ here is strong acid

NH4+ formed = 10 mmol

Volume of Solution = 100 + 100 = 200 mL

Ka of NH4+ = Kw/Kb = 1.0E-14/1.8E-5 = 5.556*10^-10

concentration ofNH4+,c = 10 mmol/200 mL = 0.05 M

NH4+ + H2O -----> NH3 + H+

5*10^-2 0 0

5*10^-2-x x x

Ka = [H+][NH3]/[NH4+]

Ka = x*x/(c-x)

Assuming x can be ignored as compared to c

So, above expression becomes

Ka = x*x/(c)

so, x = sqrt (Ka*c)

x = sqrt ((5.556*10^-10)*5*10^-2) = 5.27*10^-6

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

so, x = 5.27*10^-6 M

[H+] = x = 5.27*10^-6 M

use:

pH = -log [H+]

= -log (5.27*10^-6)

= 5.2782

Answer: 5.28

4
A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10
M HNO3. Determine the pH of the
solution after the addition of 100.0 mL of HNO3. The
Kb of NH3 is 1.8 ×
10-5.
8.72
6.58
3.44
10.56
5.28

A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3.
Determine the pH of the solution after the addition of 100.0 mL of
HNO3. The Kb of NH3 is 1.8 × 10-5.
Please show work. a) 10.56 b) 5.28 c) 6.58 d) 8.72 e) 3.44

A 100.0 mL sample of 0.20 M HF is titrated with 0.10 M KOH.
Determine the pH of the solution after the addition of 95 mL of
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0.500 M HNO3. Calculate the pH after the addition of 25.0 mL of
HNO3.

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is titrated with 0.500 M HNO3. Calculate the pH after the
addition of 15.0 mL of HNO3.

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A. 0.0 mL
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NAME _____________________________
Quiz2 Ch 16
1) A 100.0 mL sample of 0.20 M HF is titrated with 0.10 M KOH.
Determine the pH of the solution before the addition of any KOH.
The Ka of HF is 3.5 x 10-4.
A) 4.15
B) 0.70
C) 2.08
D) 3.46
E) 1.00
2) A 100.0 mL sample of 0.20 M HF is titrated with 0.10 M KOH.
Determine the pH of the solution after the addition of 100.0 mL of
KOH....

A 100.0 mL sample of 0.20 M HF is titrated with 0.10 M KOH.
Determine the pH of the solution after the addition of 200.0mL of
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