Determine the pH of a 0.4 M NaF solution at 25°C. The Ka of HF is...

Question

Question

Determine the pH of a 0.4 M NaF solution at 25°C. The Ka of HF is...

Determine the pH of a 0.4 M NaF solution at 25°C. The Ka of HF is 3.5x10-5.

science chemistry

Add a comment Improve this question Transcribed image text

Answer 1

Answer #1

use:

Kb = Kw/Ka

Kw is dissociation constant of water whose value is 1.0*10^-14 at 25 oC

Kb = (1.0*10^-14)/Ka

Kb = (1.0*10^-14)/3.5*10^-5

Kb = 2.857*10^-10

F- dissociates as

F- + H2O -----> HF + OH-

0.4 0 0

0.4-x x x

Kb = [HF][OH-]/[F-]

Kb = x*x/(c-x)

Assuming x can be ignored as compared to c

So, above expression becomes

Kb = x*x/(c)

so, x = sqrt (Kb*c)

x = sqrt ((2.857*10^-10)*0.4) = 1.069*10^-5

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

so, x = 1.069*10^-5 M

use:

pOH = -log [OH-]

= -log (1.069*10^-5)

= 4.971

use:

PH = 14 - pOH

= 14 - 4.971

= 9.029

Answer: 9.03

Add a comment

Answer 2

Similar Homework Help Questions

Calculate the pH of a 0.10-M solution of sodium fluoride (NaF) at 25°C. Ka (HF) =...

Calculate the pH of a 0.10-M solution of sodium fluoride (NaF) at 25°C. Ka (HF) = 6.6x10^-4 (Please explain all steps and reasoning)
Determine the pH of a 0.22 M NaF solution. The Ka of HF is 3.5 × 10-5

Determine the pH of a 0.22 M NaF solution. The Ka of HF is 3.5 × 10-5
Calculate the pH of a 3.51×10-3 M solution of NaF, given that the Ka of HF...

Calculate the pH of a 3.51×10-3 M solution of NaF, given that the Ka of HF = 6.80 x 10-4 at 25°C.

Calculate the pH of a 3.27×10-3 M solution of NaF, given that the Ka of HF...

Calculate the pH of a 3.27×10-3 M solution of NaF, given that the Ka of HF = 6.80 x 10-4 at 25°C.
What is the pH of a buffer solution that contains 0.100 M HF and 0.403 M...

What is the pH of a buffer solution that contains 0.100 M HF and 0.403 M NaF? The Ka of HF is 3.5x10-4.
A buffer solution contains 1.0 M HF and 1.0 M NaF. The ka for HF is...

A buffer solution contains 1.0 M HF and 1.0 M NaF. The ka for HF is 7.2x10-5. 0.10 moles of HCl are added to 1 liter of the buffer. The pH of the resulting solution is a) 4.05 b) 4.14 c) 4.23 d) 4.74

Ka for HF(aq) is 3.5x10^-4. What ratio [HF]/[NaF] is needed to make a buffer with pH=4.0?

Ka for HF(aq) is 3.5x10^-4. What ratio [HF]/[NaF] is needed to make a buffer with pH=4.0?
Determine the pH of a solution that is 1.00 L of 0.100 M HF and 0.100 M NaF after 0.50 mole of solid KOH has been added to the solution. Ka(HF) = 3.5×10-4

Determine the pH of a solution that is 1.00 L of 0.100 M HF and 0.100 M NaF after 0.50 mole of solid KOH has been added to the solution. Ka(HF) = 3.5×10-4
What is the pH of 44.3 ml of a solution which is 0.26 M in NaF and 0.33 M in HF? For HF use Ka=6.8x10^-4

What is the pH of 44.3 ml of a solution which is 0.26 M in NaF and 0.33 M in HF? For HF use Ka=6.8x10^-4

1.15 mol HF is added to enough 0.202-M NaF solution to give a final volume of 2.7 L. What is the pH of the resulting sol...

1.15 mol HF is added to enough 0.202-M NaF solution to give a final volume of 2.7 L. What is the pH of the resulting solution given that the Ka of HF is 3.5x10-4 under these conditions? 2.76 1.75 0.37 3.50 3.13

Determine the pH of a 0.4 M NaF solution at 25°C. The Ka of HF is...

Homework Answers

Add Answer to:
Determine the pH of a 0.4 M NaF solution at 25°C. The Ka of HF is...

Post as a guest

Earn Coins

Calculate the pH of a 0.10-M solution of sodium fluoride (NaF) at 25°C. Ka (HF) =...

Determine the pH of a 0.22 M NaF solution. The Ka of HF is 3.5 × 10-5

Calculate the pH of a 3.51×10-3 M solution of NaF, given that the Ka of HF...

Calculate the pH of a 3.27×10-3 M solution of NaF, given that the Ka of HF...

What is the pH of a buffer solution that contains 0.100 M HF and 0.403 M...

A buffer solution contains 1.0 M HF and 1.0 M NaF. The ka for HF is...

Ka for HF(aq) is 3.5x10^-4. What ratio [HF]/[NaF] is needed to make a buffer with pH=4.0?

Determine the pH of a solution that is 1.00 L of 0.100 M HF and 0.100 M NaF after 0.50 mole of solid KOH has been added to the solution. Ka(HF) = 3.5×10-4

What is the pH of 44.3 ml of a solution which is 0.26 M in NaF and 0.33 M in HF? For HF use Ka=6.8x10^-4

1.15 mol HF is added to enough 0.202-M NaF solution to give a final volume of 2.7 L. What is the pH of the resulting sol...

Determine the pH of a 0.4 M NaF solution at 25°C. The Ka of HF is...

Homework Answers

Add Answer to: Determine the pH of a 0.4 M NaF solution at 25°C. The Ka of HF is...

Post as a guest

Earn Coins

Add Answer to:
Determine the pH of a 0.4 M NaF solution at 25°C. The Ka of HF is...