Exercise 15.50 Part A Calculate [H3O+] and [OH?] for each of the following solut

Question

Exercise 15.50

Part A

Calculate [H3O+] and [OH?] for each of the following solutions.

(i)

pH= 8.60

Express your answer using two significant figures. Enter your answers numerically separated by a comma.

ANSWER:

[H3O+], [OH?] =

M

(ii)

pH= 11.20

Express your answer using two significant figures. Enter your answers numerically separated by a comma.

ANSWER:

[H3O+], [OH?] =

M

(iii)

pH= 2.83

Express your answer using two significant figures. Enter your answers numerically separated by a comma.

ANSWER:

[H3O+], [OH?] =

M

Part B

(i)

Calculate the percent ionization of a 0.15M formic acid solution in pure water.

Express your answer using two significant figures.

(ii)

Calculate the percent ionization of a 0.15M formic acid solution in a solution containing 0.10M potassium formate.

Express your answer using two significant figures.

(iii)

Explain the difference in percent ionization in the two solutions.

Part C

Calculate the pH of the solution that results from each of the following mixtures.

(i)

140.0mL of 0.27M HF with 230.0mL of 0.31M NaF

Express your answer using two decimal places.

ANSWER:

pH =

(ii)

185.0mL of 0.11M C2H5NH2 with 285.0mL of 0.22M C2H5NH3Cl

Express your answer using two decimal places.

ANSWER:

pH =

Part D

For each of the following solutions, calculate the initial pH and the final pH after adding 0.005 mol of NaOH.

(i)For 250.0mL of pure water, calculate the initial pH and the final pH after adding 0.005 mol of NaOH.

Express your answers using two decimal places separated by a comma.

ANSWER:

pHinitial, pHfinal =

(ii)

For 250.0mL of a buffer solution that is 0.205M in HCHO2 and 0.315M in KCHO2, calculate the initial pH and the final pH after adding 0.005 mol of NaOH.

Express your answers using two decimal places separated by a comma.

ANSWER:

pHinitial, pHfinal =

(iii)

For 250.0mL of a buffer solution that is 0.270M in CH3CH2NH2 and 0.250M in CH3CH2NH3Cl, calculate the initial pH and the final pH after adding 0.005 mol of NaOH.

Express your answers using two decimal places separated by a comma.

ANSWER:

pHinitial, pHfinal =

[H3O+], [OH?] =

M

Explanation / Answer

Paert A....

(i). pH = 8.60

pH = - log[H3O+]

8.60 =  - log[H3O+]

[H3O+] = 10-8.60

[H3O+] = 2.511X10-9 M

[H3O+][OH-] = kw

2.511X10-9[OH-] = 10-14

[OH-] = 3.98X10-6 M

(ii). pH = 11.20

[H3O+] = 10- pH

[H3O+] = 10-11.20

[H3O+] = 6.30X10-12 M

[OH-] = 10-14/ [H3O+]

= 10-14/ 6.30X10-12 M

[OH-] = 1.58X10-3 M

(iii). pH = 2.83

  [H3O+] = 10- pH

  [H3O+] = 10-2.83

  [H3O+] = 1.47X10-3 M

[OH-] = 10-14/[H3O+]

  [OH-] = 10-14/1.47X10-3 M

  [OH-] = 6.80X10-12 M

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