Question

Be sure to answer all parts. Calculate the pH during the titration of 40.00 mL of 0.1000 M HCl with 0.1000 M NaOH solution af

1 0
Add a comment Improve this question Transcribed image text
Answer #1

a)when 25.0 mL of NaOH is added

Given:

M(HCl) = 0.1 M

V(HCl) = 40 mL

M(NaOH) = 0.1 M

V(NaOH) = 25 mL

mol(HCl) = M(HCl) * V(HCl)

mol(HCl) = 0.1 M * 40 mL = 4 mmol

mol(NaOH) = M(NaOH) * V(NaOH)

mol(NaOH) = 0.1 M * 25 mL = 2.5 mmol

We have:

mol(HCl) = 4 mmol

mol(NaOH) = 2.5 mmol

2.5 mmol of both will react

remaining mol of HCl = 1.5 mmol

Total volume = 65.0 mL

[H+]= mol of acid remaining / volume

[H+] = 1.5 mmol/65.0 mL

= 2.308*10^-2 M

use:

pH = -log [H+]

= -log (2.308*10^-2)

= 1.6368

Answer: 1.64

b)when 39.0 mL of NaOH is added

Given:

M(HCl) = 0.1 M

V(HCl) = 40 mL

M(NaOH) = 0.1 M

V(NaOH) = 39 mL

mol(HCl) = M(HCl) * V(HCl)

mol(HCl) = 0.1 M * 40 mL = 4 mmol

mol(NaOH) = M(NaOH) * V(NaOH)

mol(NaOH) = 0.1 M * 39 mL = 3.9 mmol

We have:

mol(HCl) = 4 mmol

mol(NaOH) = 3.9 mmol

3.9 mmol of both will react

remaining mol of HCl = 0.1 mmol

Total volume = 79.0 mL

[H+]= mol of acid remaining / volume

[H+] = 0.1 mmol/79.0 mL

= 1.266*10^-3 M

use:

pH = -log [H+]

= -log (1.266*10^-3)

= 2.8976

Answer: 2.90

c)when 55.0 mL of NaOH is added

Given:

M(HCl) = 0.1 M

V(HCl) = 40 mL

M(NaOH) = 0.1 M

V(NaOH) = 55 mL

mol(HCl) = M(HCl) * V(HCl)

mol(HCl) = 0.1 M * 40 mL = 4 mmol

mol(NaOH) = M(NaOH) * V(NaOH)

mol(NaOH) = 0.1 M * 55 mL = 5.5 mmol

We have:

mol(HCl) = 4 mmol

mol(NaOH) = 5.5 mmol

4 mmol of both will react

remaining mol of NaOH = 1.5 mmol

Total volume = 95.0 mL

[OH-]= mol of base remaining / volume

[OH-] = 1.5 mmol/95.0 mL

= 1.579*10^-2 M

use:

pOH = -log [OH-]

= -log (1.579*10^-2)

= 1.8016

use:

PH = 14 - pOH

= 14 - 1.8016

= 12.1984

Answer: 12.20

Add a comment
Know the answer?
Add Answer to:
Be sure to answer all parts. Calculate the pH during the titration of 40.00 mL of...
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions
ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT