Question

Calculate the pH of a buffer, consisting of 0.42 M HF and 0.42 M F -,...

Calculate the pH of a buffer, consisting of 0.42 M HF and 0.42 M F -, before and after addition of 0.44 g of NaOH to 1.0 L of the buffer (Ka of HF = 6.8 ✕ 10-4).

(a) before

(b) after

Science   Chemistry   
0 0
Add a commentTranscribed image text
Next >

Homework Answers

Answer #1

we know that

pKa = -log Ka = -log 6.8 x 10-4

pKa = 3.16749


for buffers

pH = pKa + log [conjugate base / acid]

in this case

pH = pKa + log [ F-/HF]

a) before adding NaOH

pH = 3.16749 + log[ 0.42 / 0.42]

pH = 3.16749 + log 1

pH = 3.16749 + 0

pH = 3.16749

so

pH of the buffer is 3.16749

b)

now

moles = mass / molar mass

moles of NaOH = 0.44 / 40 = 0.11

now

concentration = moles / volume

so

[NaOH] = 0.11 / 1 = 0.11

now

HF + OH- --> F- + H20

we can see that

[HF] reacted = [NaoH] added = 0.11

[F-] formed = [NaOH] added = 0.11

now finally

[HF] = 0.42 - 0.11 = 0.31

[F-] = 0.42 + 0.11 = 0.53

so

pH = pKa + log [F-/HF]

pH = 3.16749 + log [0.53 / 0.31]

pH = 3.4

so

the pH after addition of NaoH is 3.4

0 0
Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Log In

Sign Up

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
A 1.00 L buffer solution is composed of 0.250 M HF and 0.250 M NaF. Calculate...
A 1.00 L buffer solution is composed of 0.250 M HF and 0.250 M NaF. Calculate the 13)______ pH of the solution after the addition of 0.150 moles of solid NaOH. Assume no volume change upon the addition of base. The Ka for HF is 3.5 × 10-4.
A)Calculate the pH of 0.100 L of a buffer solution that is 0.27 M in HF...
A)Calculate the pH of 0.100 L of a buffer solution that is 0.27 M in HF (Ka = 3.5 x 10-4 ) and 0.51 M in NaF?B)What is the pH after adding 0.004 mol of HNO3 to the buffer described in Part A? C)What is the pH after adding 0.004 mol of KOH to the buffer described in Part A?
Calculate pH after the addition of 0.10 mole of NaOH to a 500 ml buffer made...
Calculate pH after the addition of 0.10 mole of NaOH to a 500 ml buffer made up of 0.500 M HF (Ka = 6.8 x 10^-4) & 0.500 M NaF? Assume no change in volume of solution upon addition of base.
A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in LiF. Calculate...
A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in LiF. Calculate the pH of the solution after the addition of 0.150 moles of solid LiOH. Assume no volume change upon the addition of base. The Ka for HF is 3.5x10^-4. Please show how to work out this problem.
A buffer consists of 0.72-M propanoic acid (ka = 1.4 × 10-5) and 0.84-M sodium propanoate....
A buffer consists of 0.72-M propanoic acid (ka = 1.4 × 10-5) and 0.84-M sodium propanoate. a.) Calculate the pH of this buffer. b.) Calculate the pH after the addition of 6.8 mL of 0.10–M HCL to 0.010 L of the buffer. c.) Calculate the pH after the addition of 8.4 mL of 1.0–M HCL to 0.010 L of the buffer.
1.) A buffer solution contains 0.455 M NH4Cl and 0.295 M NH3 (ammonia). Determine the pH...
1.) A buffer solution contains 0.455 M NH4Cl and 0.295 M NH3 (ammonia). Determine the pH change when 0.085 mol NaOH is added to 1.00 L of the buffer. pH after addition − pH before addition = pH change = 2.) Determine the pH change when 0.044 mol HNO3 is added to 1.00 L of a buffer solution that is 0.462 M in HF and 0.218 M in F-. pH after addition − pH before addition = pH change =
The Ka value for HF is 3.5×10?4. Calculate the change in pH when 2.0×10?2mol of NaOH...
The Ka value for HF is 3.5×10?4. Calculate the change in pH when 2.0×10?2mol of NaOH is added to 0.50 L of a buffer solution that is 0.15 M in HF and 0.20 M in NaF.
Calculate the pH of 1.00 L of the buffer 0.95 M CH3COONa/0.98 M CH3COOH before and...
Calculate the pH of 1.00 L of the buffer 0.95 M CH3COONa/0.98 M CH3COOH before and after the addition of the following species. (Assume there is no change in volume.) (a) pH of starting buffer: (b) pH after addition of 0.070 mol NaOH: (c) pH after further addition of 0.126 mol HCl:
Calculate the pH of the buffer solution (1.00 M HNO2 and 1.00 M NaNO2) after 0.20...
Calculate the pH of the buffer solution (1.00 M HNO2 and 1.00 M NaNO2) after 0.20 mol of NaOH is added to 1.00 L of buffer solution (Ka = 4.0 x 10^-4)
Part A Consider a buffer solution that is 0.50 M in NH3 and 0.20 M in...
Part A Consider a buffer solution that is 0.50 M in NH3 and 0.20 M in NH4Cl. For ammonia, pKb=4.75.​ Calculate the pH of 1.0 L of the original buffer, upon addition of 0.190 mol of solid NaOH. Part B A 1.0-L buffer solution contains 0.100 mol HC2H3O2 and 0.100 mol NaC2H3O2. The value of Ka for HC2H3O2 is 1.8×10−5.​ Calculate the pH of the solution, upon addition of 0.030 mol of NaOH to the original buffer. (I will leave...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT