# Buffer Solution, pH and Concentration

1- Solve an equilibrium problem (using an ICE table) to calculate the pH of each solution:a solution that is 0.165M in HC 2 H 3 O 2 and 0.120M in KC 2 H 3 O 2. Express your answer using two decimal places.

2- A buffer contains significant amounts of ammonia and ammonium chloride.Write an equation showing how this buffer neutralizes added acid (HI). Express your answer as a chemical equation.

3- A buffer contains significant amounts of ammonia and ammonium chloride. Write an equation showing how this buffer neutralizes added base (CsOH). Express your answer as a chemical equation.

4- Determine whether mixing each pair of solutions results in a buffer.

75.0 mL of 0.10 MHF ; 55.0 mL of 0.15 MNaF

150.0 mL of 0.10 MHF ; 135.0 mL of 0.175 MHCl

150.0 mL of 0.10 MHF ; 135.0 mL of 0.175 MHCl

5- A 1.0-L buffer solution is 0.105M in HNO 2 and 0.145M in NaNO 2 . Determine the concentrations of HNO 2 and NaNO 2 after addition of 1.4g HCl .

© BrainMass Inc. brainmass.com October 25, 2018, 8:50 am ad1c9bdddfhttps://brainmass.com/chemistry/general-chemistry/buffer-solution-ph-concentration-553718

#### Solution Preview

Please see the attachment.

Ionics Part 2

1- Solve an equilibrium problem (using an ICE table) to calculate the pH of each solution: a solution that is 0.165M in HC2H3O2 and 0.120M in KC2H3O2. Express your answer using two decimal places.

You can use the ICE table method to do it ... or you can use the 'x is small' method. Using the Henderson Hasselbach equation:

pH = pKa + log [ base / acid ] (tricky part is knowing which is base and which is acid)

pH = - log(1.8 * 10^-5) + log (0.120/ 0.165) = 4.61

2- A buffer contains significant amounts of ammonia and ammonium chloride. ...

#### Solution Summary

This solution offers succinct and logical answers to some problems related to buffer solution and all steps of the calculation are shown.

What is the pH of a solution of 0.49 M acid and 0.29 M of its conjugate base if the ionization constant is 5.92 x 10-8?

1) What is the pH of a solution of 0.49 M acid and 0.29 M of its conjugate base if the ionization constant is 5.92 x 10-8?

A. 7.72

B. 7.98

C. 7.46

D. 8.21

E. 7.00

2) What is the pH of a solution of 0.81 M acid and 0.35 M of its conjugate base if the ionization constant is 5.45 x 10-8?

A. 7.33

B. 6.42

C. 7.63

D. 6.70

E. 6.90

3) A 25.00 mL sample of 0.100 M CH3CO2H is titrated with 0.100 M NaOH. What is the pH of the solution at the points where 24.5 and 25.5 mL of NaOH have been added? (Ka = 1.8 x 10-5)

A. 6.43, 11.00

B. 7.00, 8.00

C. 6.44, 9.85

D. 6.13, 9.85

E. 6.34, 11.00

4) What is the molarity of a saturated solution of BaSO4? (Ksp = 1.1 x 10-10)

A. 2.0 x 10-5

B. 5.0 x 10-6

C. 1.0 x 10-5

D. 1.1 x 10-10

E. 2.2 x 10-10

5) What is the molarity of a saturated solution of AgCl? (Ksp = 1.8 x 10-10)

A. 2.6 x 10-5

B. 9.0 x 10-9

C. 1.3 x 10-5

D. 1.8 x 10-10

E. 6.5 x 10-6

6) Which of the following when dissolved in water has the highest concentration of magnesium ion?

A. MgC2O4; Ksp = 9.3 x 10-3 M2

B. MgOH2; Ksp = 1.8 x 10-4 M3

C. Mg3(AsO4)2; Ksp = 2.0 x 10-20 M5

D. Ion concentrations are equivalent

E. Not enough information provided

7) Which of the following when dissolved in water has the highest concentration of barium ion?

A. Ba3(PO4)2; Ksp = 1.1 x 10-13 M5

B. BaF2; Ksp = 1.7 x 10-6 M3

C. BaCO3; Ksp = 8.1 x 10-9 M2

D. Ion concentrations are equivalent

E. Not enough information provided

8) What is the concentration (M) of Mg2+ when MgC2O4 (Ksp = 8.5 x 10-5) begins to precipitate from a solution that is 0.020 M in C2O42-?

A. 1.7 x 10-6

B. 1.7 x 10-4

C. 4.2 x 10-3

D. 4.2 x 10-5

E. 3.4 x 10-4

9) What is the molar solubility of MgC2O4 (Ksp = 8.5 x 10-5) in a 0.020 M C2O42- solution?

A. 3.4 x 10-4

B. 1.7 x 10-6

C. 4.2 x 10-3

D. 4.2 x 10-5

E. 1.7 x 10-4

10) What is the concentration of Cu2+ in a solution that is 0.10 M Cu(NH3)42+? (Kf = 1.2 x 1012)

A. 8.5 x 10-5

B. 2.8 x 10-4

C. 8.0 x 10-4

D. 5.1 x 10-4

E. 3.8 x 10-4

11) What is the concentration of Ni2+ in a solution that is 1.0 M Ni(NH3)62+? (Kf = 1.8 x 108)

A. 7.2 x 10-4

B. 2.1 x 10-4

C. 1.4 x 10-2

D. 3.2 x 10-4

E. 5.8 x 10-4

12) What is the pH of a solution of 0.65 M acid and 0.51 M of its conjugate base if the pKa = 5.30?

A. 5.19

B. 6.05

C. 5.62

D. 5.85

E. 5.41

13) What is the pH of a solution of 0.17 M acid and 0.81 M of its conjugate base if the pKa = 8.62?

A. 9.30

B. 7.94

C. 9.52

D. 9.68

E. 8.58

14) What is the hydronium ion concentration of a solution of 0.720 M acid and 0.240 M of its conjugate base if the ionization constant is 4.38 x 10-6?

A. 3.15 x 10-5

B. 1.31 x 10-5

C. 1.05 x 10-6

D. 1.46 x 10-6

E. 6.08 x 10-6

15) What is the hydronium ion concentration of a solution of 0.700 M acid and 0.440 M of its conjugate base if the ionization constant is 3.59 x 10-8?

A. 1.13 x 10-7

B. 5.71 x 10-8

C. 2.47 x 10-7

D. 2.26 x 10-8

E. 8.98 x 10-8

16) The _______ of a titration occurs when the indicator changes color.

A. equivalence point

B. endpoint

C. neutralization point

D. molar solubility

E. none of the above

17) The point at which an acid has completely reacted with or been neutralized by the base is known as the

A. equivalence point

B. endpoint

C. neutralization point

D. solubility

E. none of the above

18) Which 0.1 M solution bellow will turn phenolphthalein pink?

A. HBr(aq)

B. CO2(aq)

C. LiOH(aq)

D. CH3OH(aq)

E. none of the above

19) The following data were collected at the endpoint of a titration performed to find the molarity of an HCl solution.

Volume of acid (HCl) used = 14.4 mL

Volume of base (NaOH) used = 22.4 mL

Molarity of standard base (NaOH) = 0.20 M

What is the molarity of the acid solution?

A. 1.6 M

B. 0.64 M

C. 0.31 M

D. 0.13 M

E. 0.25 M

20) A 25.00 mL sample of 0.100 M CH3CO2H is titrated with 0.100 M NaOH. What is the pH of the solution at the points where 25.0 and 25.5 mL of NaOH have been added. (Ka = 1.8 x 10-5)

A. 7.00, 8.00

B. 8.72, 9.85

C. 7.00, 9.85

D. 7.00, 10.00

E. 8.72, 11.00