Question

Part A

Calculate the pH of 0.100 L of a buffer solution that is 0.23 M in HF and 0.55 M in NaF.

Part B

Calculate pH of the solution on addition of the following. 0.004 mol of HNO3

Part C

Calculate pH of the solution on addition of the following. 0.002 mol of KOH

Answer #1

Part A

They have given pH , volume of HF, and NaF. We can use Henderson Hasselbalch equation and find out the pH.

Equation

Lets plug given values in above equation and get the value of pH.

Pka = - log ka

Ka of HF = 6.6E-04

Therefore pka = -log ( 6.6 E-4 )

= 3.18

Lets use this value

Therefore the pH of the solution would be 3.55

Part B

In this part we have to find pH after addition of 0.004 moles of HNO3

Since HNO3 is acid so it will reacts with base and forms acid (HF) back.

Lets show the reaction of HNO3 with base.

Number of moles HF formed equal to number of moles of F- disappears and both are equal to moles of HNO3.

Now lets calculated equilibrium molarity of HF and F

[NaF-] = [F-] = 0.51 M

Lets use Same equation (Henderson Hasselbalch euqution)

Part C

Now we have to use moles of base and find pH. We use same procedure. Here moles of acid will decrease and moles of base will decrease. Lets show the reaction.

KOH + HF--- > KF (aq) + H2O (l)

This gives mole ration (1:1)

So the pH of this solution is 3.61

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?

Part A
Calculate the pH of 0.100 L of a buffer solution that is 0.23 M
in HF (Ka = 3.5 x 10-4 ) and 0.45 M in NaF.
Express your answer using three significant figures.
pH =
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Part B
What is the pH after adding 0.001 mol of HNO3 to the buffer
described in Part A?
Express your answer using three significant figures.
pH =
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Part C
What is the pH after adding...

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...

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.

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
=

a) The pKa of HF is 3.17. Calculate the pH of a 1.00 L solution
that is 1.00 M HF and 1.50 M NaF.
b) What is the pH of this solution after addition of 50.0 mL of
10.0 M HCl?

A buffer is created with 0.100 moles of HF and 0.100 moles of
NaF in a 1.00 L aqueous solution. This buffer has a pH of 3.15. How
many moles of NaOH would you need to add to this buffer in order to
obtain a solution with a pH of 3.80. (Ka of HF = 7.1 x 10–4)

What is the pH of a buffer solution (0.100 L containing 0.166
mol/L pyruvic acid (Ka = 4.1x10-3)) and 0.117
mol L-1 sodium pyruvate before and after the addition of
0.010 L of 0.10 mol/L HCl?

A buffer solution contains 0.263 M CH3NH3Cl and 0.339 M CH3NH2
(methylamine). Determine the pH change when 0.076 mol HNO3 is added
to 1.00 L of the buffer. pH after addition − pH before addition =
pH change =
A buffer solution contains 0.333 M
NaH2PO4 and
0.221 M
Na2HPO4.
Determine the pH change when
0.046 mol HClO4 is
added to 1.00 L of the buffer.
pH change =

1. A buffer solution contains 0.378 M KHCO3 and 0.268 M K2CO3.
Determine the pH change when 0.094 mol KOH is added to 1.00 L of
the buffer.
pH after addition − pH before addition = pH change =
2. Determine the pH change when
0.066 mol HI is added to
1.00 L of a buffer solution that is
0.345 M in CH3COOH and
0.262M in
CH3COO-.
pH after addition − pH before addition = pH change
=

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