menu
bartleby
search
close search
Hit Return to see all results
close solutoin list

Sketch the titration curve for a weak base titrated by a strong acid. Weak base–strong acid titration problems also follow a two-step procedure. What reaction takes place in the stoichiometry part of the problem? What is assumed about this reaction? At the various points in your titration curve, list the major species present after the strong acid (HNO 3 , for example) reacts to completion with the weak base, B. What equilibrium problem would you solve at the various points in your titration curve to calculate the pH? Why is pH < 7.0 at the equivalence point of a weak base–strong acid titration? If pH = 6.0 at the halfway point to equivalence, what is the K b value for the weak base titrated? Compare and contrast the titration curves for a strong base–strong acid titration and a weak base–strong acid titration.

BuyFindarrow_forward

Chemistry: An Atoms First Approach

2nd Edition
Steven S. Zumdahl + 1 other
Publisher: Cengage Learning
ISBN: 9781305079243

Solutions

Chapter
Section
BuyFindarrow_forward

Chemistry: An Atoms First Approach

2nd Edition
Steven S. Zumdahl + 1 other
Publisher: Cengage Learning
ISBN: 9781305079243
Chapter 14, Problem 8RQ
Textbook Problem
5 views

Sketch the titration curve for a weak base titrated by a strong acid. Weak base–strong acid titration problems also follow a two-step procedure. What reaction takes place in the stoichiometry part of the problem? What is assumed about this reaction? At the various points in your titration curve, list the major species present after the strong acid (HNO3, for example) reacts to completion with the weak base, B. What equilibrium problem would you solve at the various points in your titration curve to calculate the pH? Why is pH < 7.0 at the equivalence point of a weak base–strong acid titration? If pH = 6.0 at the halfway point to equivalence, what is the Kb value for the weak base titrated? Compare and contrast the titration curves for a strong base–strong acid titration and a weak base–strong acid titration.

Interpretation Introduction

Interpretation: The titration curve for the titration of a weak base by a strong acid is to be sketched. The reaction takes place in the stoichiometry part of the problem is to be stated. The assumption about this reaction is to be stated. The major species after the titration are to be listed. The equilibrium problem, at the various points in the titration curve to calculate the pH is to be stated. The reason for the value of pH is less than 7 at the equivalence point for the titration of weak acid-strong base titration is to be stated. The value of Kb for this titration if pH is equal to six at the halfway point to equivalence is to stated. The titration curves for a strong base –strong acid titration are to be compared and to be stated.

Concept introduction: The reaction between an acid and a base takes place with the formation of a salt and a water molecule.

The hydrogen ion concentration of the solution is known as pH of the solution.

It is the negative logarithm of Hydrogen ion concentration.

At the equivalence point the moles of the acid and base in the solution are same.

At the half equivalence point the concentration of titrant is just half of the initial amount.

For the given value of dissociation constant the pH=pKa .

To determine: The sketch of the titration curve for a weak base -strong acid titration; The reaction takes place in stoichiometric part of the problem; The assumption about this reaction; The list of the major species present after the completion reaction between strong acid with weak base; The equilibrium problem which involve at the various points in the calculation of pH ; The reason for the value of pH<7 at the equivalence point in the weak base –strong acid titration. The value of Kb for this titration if the pH at the halfway point to equivalence is equal to 6.0 ; The comparison between the titration curves of a strong base –strong acid titration and a weak base-strong acid titration.

Explanation of Solution

Explanation

A titration curve is plot of pH Vs volume of titrant. In such plots the pH is taken as independent variable while volume of titrant is taken as dependent variable. Such plots are also known as pH curves.

In the calculation of weak base -strong acid titration, the two step procedure is involved. First one is stoichiometric problem and second is equilibrium problem. The step procedure is as follows,

  1. i. Stoichiometric problem: The completion reaction is to be assumed in the weak base-strong acid titration.
  2. ii. Equilibrium problem: The pH at the equivalence point is determined.

The titration of 100.0mlof0.050M Ammonia with 0.10MHNO3 is to be assumed. The pH curve for this titration is given as,

Figure 1

The equivalence point occurs on the addition of 50mlofHNO3 . Here the amount of hydride ion is exactly equal to the original amount of base. At the equivalence point the pH is less than 7 because the ammonium ion present at this point is an acid and it reacts with water to produce hydroxide ion.

The reaction involves in the part of stoichiometric problem is given as,

NH3(aq)+H+(aq)NH4+(aq)

Here the amount of Hydride ion is lesser than the acid. Therefore, it consumed completely and called as limiting reactant.

The pH at various points is calculated by representing the volumes of added HNO3 as,

When 0.0ml0.10MHNO3 has been added.

In this situation only weak base that is Ammonia is present in the solution.

Therefore the equilibrium of NH3 is represented by the equation,

NH3+H2ONH4++OH

Morality of NH3 is 0.05M . The number of moles is calculated by the formula,

n=C×V

Where,

  • n is the number of moles.
  • C is the concentration of the solution.
  • V is the volume of the solution.

Substitute the values of concentrations and volume in the above equation.

n=C×V=0.050M×1001000L=0.005mol

Now x is supposed to be the change in moles. The equilibrium reaction with the calculated moles is expressed in ICE (initial, change, equilibrium) table as,

NH3+H2ONH4++OH-Initialmol0.00500Changeinmolx+x+xEquilibriummol0.005xxx

The base dissociation constant (Kb) for this reaction is written as,

Kb=(x)(x)(0.005x)

Substitute the value of Kb in the above equation,

Kb=(x)(x)(0.005x)1.8×105=x2(0.005x)

Simplify the above equation.

x=9.0×106

Therefore, the concentration of OH is 9.0×106 .

The [OH] concentration in terms of Kw is written as,

[OH][H+]=Kw(9.0×106)[H+]=1.0×1014[H+]=1.0×10149.0×106[H+]=1.1×109

The pH of the above given hydride ion is calculated as,

pH=log(H+)=log(1.1×109)=log(1.1)+9=8.95_

When 10.0ml0.10MHNO3 has been added.

The stoichiometric problem part is represented as,

HNO3+NH3NH4++NO3Beforereaction50ml×0.10M=5.0mmol100.0ml×0.050M=5.0mmol0Afterrecation05.01.0=4.0mmol1.0mmol

The equilibrium problem part is given below.

Acetic acid is much stronger acid than water and NO3 is the conjugate base of HNO3 . The pH is determined as,

HNO3(aq)NO3-(aq)+H+(aq)Ka=[H+][NO3-][HNO3] (1)

Where,

  • Ka is the acid dissociation constant

Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started

Chapter 14 Solutions

Chemistry: An Atoms First Approach
Show all chapter solutions
add
Ch. 14 - What are the major species in solution after...Ch. 14 - A friend asks the following: Consider a buffered...Ch. 14 - Mixing together solutions of acetic acid and...Ch. 14 - Could a buffered solution be made by mixing...Ch. 14 - Sketch two pH curves, one for the titration of a...Ch. 14 - Sketch a pH curve for the titration of a weak acid...Ch. 14 - You have a solution of the weak acid HA and add...Ch. 14 - You have a solution of the weak acid HA and add...Ch. 14 - The common ion effect for weak acids is to...Ch. 14 - Consider a buffer solution where [weak acid] ...Ch. 14 - A best buffer has about equal quantities of weak...Ch. 14 - Consider the following pH curves for 100.0 mL of...Ch. 14 - An acid is titrated with NaOH. The following...Ch. 14 - Consider the following four titrations. i. 100.0...Ch. 14 - Figure 14-4 shows the pH curves for the titrations...Ch. 14 - Acidbase indicators mark the end point of...Ch. 14 - How many of the following are buffered solutions?...Ch. 14 - Which of the following can be classified as buffer...Ch. 14 - A certain buffer is made by dissolving NaHCO3 and...Ch. 14 - A buffer is prepared by dissolving HONH2 and...Ch. 14 - Calculate the pH of each of the following...Ch. 14 - Calculate the pH of each of the following...Ch. 14 - Compare the percent dissociation of the acid in...Ch. 14 - Compare the percent ionization of the base in...Ch. 14 - Calculate the pH after 0.020 mole of HCl is added...Ch. 14 - Calculate the pH after 0.020 mole of HCl is added...Ch. 14 - Calculate the pH after 0.020 mole of NaOH is added...Ch. 14 - Calculate the pH after 0.020 mole of NaOH is added...Ch. 14 - Which of the solutions in Exercise 21 shows the...Ch. 14 - Which of the solutions in Exercise 22 is a...Ch. 14 - Calculate the pH of a solution that is 1.00 M HNO2...Ch. 14 - Calculate the pH of a solution that is 0.60 M HF...Ch. 14 - Calculate the pH after 0.10 mole of NaOH is added...Ch. 14 - Calculate the pH after 0.10 mole of NaOH is added...Ch. 14 - Calculate the pH of each of the following buffered...Ch. 14 - Calculate the pH of each of the following buffered...Ch. 14 - Calculate the pH of a buffered solution prepared...Ch. 14 - A buffered solution is made by adding 50.0 g NH4Cl...Ch. 14 - Calculate the pH after 0.010 mole of gaseous HCl...Ch. 14 - An aqueous solution contains dissolved C6H5NH3Cl...Ch. 14 - Calculate the mass of sodium acetate that must be...Ch. 14 - What volumes of 0.50 M HNO2 and 0.50 M NaNO2 must...Ch. 14 - Consider a solution that contains both C5H5N and...Ch. 14 - Calculate the ratio [NH3]/[NH4+] in...Ch. 14 - Carbonate buffers are important in regulating the...Ch. 14 - When a person exercises, muscle contractions...Ch. 14 - Consider the acids in Table 13-2. Which acid would...Ch. 14 - Consider the bases in Table 13-3. Which base would...Ch. 14 - Calculate the pH of a solution that is 0.40 M...Ch. 14 - Calculate the pH of a solution that is 0.20 M HOCl...Ch. 14 - Which of the following mixtures would result in...Ch. 14 - Which of the following mixtures would result in a...Ch. 14 - What quantity (moles) of NaOH must be added to 1.0...Ch. 14 - Calculate the number of moles of HCl(g) that must...Ch. 14 - Consider the titration of a generic weak acid HA...Ch. 14 - Sketch the titration curve for the titration of a...Ch. 14 - Consider the titration of 40.0 mL of 0.200 M HClO4...Ch. 14 - Consider the titration of 80.0 mL of 0.100 M...Ch. 14 - Consider the titration of 100.0 mL of 0.200 M...Ch. 14 - Consider the titration of 100.0 mL of 0.100 M...Ch. 14 - Lactic acid is a common by-product of cellular...Ch. 14 - Repeat the procedure in Exercise 61, but for the...Ch. 14 - Repeat the procedure in Exercise 61, but for the...Ch. 14 - Repeat the procedure in Exercise 61, but for the...Ch. 14 - Calculate the pH at the halfway point and at the...Ch. 14 - In the titration of 50.0 mL of 1.0 M methylamine,...Ch. 14 - You have 75.0 mL of 0.10 M HA. After adding 30.0...Ch. 14 - A student dissolves 0.0100 mole of an unknown weak...Ch. 14 - Two drops of indicator HIn (Ka = 1.0 109), where...Ch. 14 - Methyl red has the following structure: It...Ch. 14 - Potassium hydrogen phthalate, known as KHP (molar...Ch. 14 - A certain indicator HIn has a pKa of 3.00 and a...Ch. 14 - Which of the indicators in Fig. 14-8 could be used...Ch. 14 - Which of the indicators in Fig. 14-8 could be used...Ch. 14 - Which of the indicators in Fig. 14-8 could be used...Ch. 14 - Which of the indicators in Fig. 14-8 could be used...Ch. 14 - Estimate the pH of a solution in which bromcresol...Ch. 14 - Estimate the pH of a solution in which crystal...Ch. 14 - A solution has a pH of 7.0. What would be the...Ch. 14 - A solution has a pH of 4.5. What would be the...Ch. 14 - Derive an equation analogous to the...Ch. 14 - a. Calculate the pH of a buffered solution that is...Ch. 14 - Tris(hydroxymethyl)aminomethane, commonly called...Ch. 14 - You make 1.00 L of a buffered solution (pH = 4.00)...Ch. 14 - You have the following reagents on hand: Solids...Ch. 14 - Amino acids are the building blocks for all...Ch. 14 - Phosphate buffers are important in regulating the...Ch. 14 - What quantity (moles) of HCl(g) must be added to...Ch. 14 - Calculate the value of the equilibrium constant...Ch. 14 - The following plot shows the pH curves for the...Ch. 14 - Calculate the volume of 1.50 102 M NaOH that must...Ch. 14 - Repeat the procedure in Exercise 61, but for the...Ch. 14 - A certain acetic acid solution has pH = 2.68....Ch. 14 - A 0.210-g sample of an acid (molar mass = 192...Ch. 14 - The active ingredient in aspirin is...Ch. 14 - One method for determining the purity of aspirin...Ch. 14 - A student intends to titrate a solution of a weak...Ch. 14 - A student titrates an unknown weak acid, HA, to a...Ch. 14 - A sample of a certain monoprotic weak acid was...Ch. 14 - Consider 1.0 L of a solution that is 0.85 M HOC6H5...Ch. 14 - What concentration of NH4Cl is necessary to buffer...Ch. 14 - Consider the following acids and bases: HCO2H Ka =...Ch. 14 - Consider a buffered solution containing CH3NH3Cl...Ch. 14 - Consider the titration of 150.0 mL of 0.100 M HI...Ch. 14 - Consider the titration of 100.0 mL of 0.100 M HCN...Ch. 14 - Consider the titration of 100.0 mL of 0.200 M...Ch. 14 - Consider the following four titrations (iiv): i....Ch. 14 - Another way to treat data from a pH titration is...Ch. 14 - A buffer is made using 45.0 mL of 0.750 M HC3H5O2...Ch. 14 - A 0.400-M solution of ammonia was titrated with...Ch. 14 - What volume of 0.0100 M NaOH must be added to 1.00...Ch. 14 - Consider a solution formed by mixing 50.0 mL of...Ch. 14 - When a diprotic acid, H2A, is titrated with NaOH,...Ch. 14 - Consider the following two acids: In two separate...Ch. 14 - The titration of Na2CO3 with HCl bas the following...Ch. 14 - Consider the titration curve in Exercise 115 for...Ch. 14 - A few drops of each of the indicators shown in the...Ch. 14 - Malonic acid (HO2CCH2CO2H) is a diprotic acid. In...Ch. 14 - A buffer solution is prepared by mixing 75.0 mL of...Ch. 14 - A 10.00-g sample of the ionic compound NaA, where...Ch. 14 - Calculate the pH of a solution prepared by mixing...Ch. 14 - Consider a solution prepared by mixing the...

Additional Science Textbook Solutions

Find more solutions based on key concepts
Show solutions add
To keep up with nutrition science, the consumer should. a. seek out the health and fitness sections of newspape...

Nutrition: Concepts and Controversies - Standalone book (MindTap Course List)

How can you be sure that giant stars really are Larger than main- sequence stars?

Horizons: Exploring the Universe (MindTap Course List)

What is hereditarianism, and what is the invalid assumption it makes?

Human Heredity: Principles and Issues (MindTap Course List)

The board sandwiched between two other boards in Figure P5.97 weighs 95.5 N. If the coefficient of static frict...

Physics for Scientists and Engineers, Technology Update (No access codes included)

What is the difference between sea islands and barrier islands?

Oceanography: An Invitation To Marine Science, Loose-leaf Versin