Chemistry
9th Edition
ISBN: 9781133611097
Author: Steven S. Zumdahl
Publisher: Cengage Learning
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Chapter 15, Problem 2ALQ
A friend asks the following: “Consider a buffered solution made up of the weak acid HA and its salt NaA. If a strong base like NaOH is added, the HA reacts with the OH− to form A−. Thus the amount of acid (HA) is decreased, and the amount of base (A−) is increased. Analogously, adding HCI to the buffered solution forms more of the acid (HA) by reacting with the base (A−). Thus how can we claim that a buffered solution resists changes in the pH of the solution?” How would you explain buffering to this friend?
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Consider that 20.0 mL of 0.10 M HA (an arbitrary weak acid, Ka= 1.5 × 10−6) is titrated with 0.10 M NaOH solution. The ionization of HA in water occurs as the following.HA (aq) + H2O(l) ⇌ A-(aq) + H3O+ (aq)The neutralization reaction between HA and NaOH can be expressed as the following.
HA (aq) + NaOH (aq) ® NaA (aq) + H2O (l) Answer the following questions.
A) What will be the initial pH of the 0.10 M HA solution?
predicting the qualitative acid-base
properties of salts
Consider the following data on some weak acids and weak bases:
name
acetic acid
acid
hydrocyanic acid
solution
0.1 M NaCN
0.1 M NH C
0.1 MHONH,Br
Use this data to rank the following solutions in order of increasing pH. In other words, select a '1' next to the solution that will have the lowest pH, a 2 next to
the solution that will have the next lowest pH, and so on.
0.1 M KCH₂CO₂
K₁
formula
HCH,CO₂ 1.8x10
HCN
4.9 × 10 10
pH
choose one
X
Ű
choose one
choose one
choose one
base
3
Ċ
K₂
name formula
ammonia
NH₂ 1.8×10
hydroxylamine HONH₂ 1.1×108
Which of the following is true of a buffer solution?
Buffer solutions must have a pH over 11.0.
Buffers resist changes to their pH.
O Buffer solutions do not react with acids or bases.
Buffers must have a pH under 4.0.
Buffer solutions must have a strong color.
Chapter 15 Solutions
Chemistry
Ch. 15 - What is meant by the presence of a common ion? How...Ch. 15 - Define a buffer solution. What makes up a buffer...Ch. 15 - One of the most challenging parts of solving...Ch. 15 - A good buffer generally contains relatively equal...Ch. 15 - Draw the general titration curve for a strong acid...Ch. 15 - Instead of the titration of a strong acid by a...Ch. 15 - Sketch the titration curve for a weak acid...Ch. 15 - Sketch the titration curve for a weak base...Ch. 15 - What is an acidbase indicator? Define the...Ch. 15 - Why does an indicator change from its acid color...
Ch. 15 - What are the major species in solution after...Ch. 15 - A friend asks the following: Consider a buffered...Ch. 15 - Mixing together solutions of acetic acid and...Ch. 15 - Could a buffered solution be made by mixing...Ch. 15 - Sketch two pH curves, one for the titration of a...Ch. 15 - Sketch a pH curve for the titration of a weak acid...Ch. 15 - You have a solution of the weak acid HA and add...Ch. 15 - You have a solution of the weak acid HA and add...Ch. 15 - The common ion effect for weak acids is to...Ch. 15 - Prob. 10QCh. 15 - A best buffer has about equal quantities of weak...Ch. 15 - Consider the following pH curves for 100.0 mL of...Ch. 15 - An acid is titrated with NaOH. The following...Ch. 15 - Consider the following four titrations. i. 100.0...Ch. 15 - Figure 14-4 shows the pH curves for the titrations...Ch. 15 - Acidbase indicators mark the end point of...Ch. 15 - How many of the following are buffered solutions?...Ch. 15 - Which of the following can be classified as buffer...Ch. 15 - A certain buffer is made by dissolving NaHCO3 and...Ch. 15 - A buffer is prepared by dissolving HONH2 and...Ch. 15 - Calculate the pH of each of the following...Ch. 15 - Calculate the pH of each of the following...Ch. 15 - Compare the percent dissociation of the acid in...Ch. 15 - Compare the percent ionization of the base in...Ch. 15 - Calculate the pH after 0.020 mole of HCl is added...Ch. 15 - Calculate the pH after 0.020 mole of HCl is added...Ch. 15 - Calculate the pH after 0.020 mole of NaOH is added...Ch. 15 - Calculate the pH after 0.020 mole of NaOH is added...Ch. 15 - Which of the solutions in Exercise 21 shows the...Ch. 15 - Prob. 30ECh. 15 - Calculate the pH of a solution that is 1.00 M HNO2...Ch. 15 - Calculate the pH of a solution that is 0.60 M HF...Ch. 15 - Calculate the pH after 0.10 mole of NaOH is added...Ch. 15 - Calculate the pH after 0.10 mole of NaOH is added...Ch. 15 - Calculate the pH of each of the following buffered...Ch. 15 - Calculate the pH of each of the following buffered...Ch. 15 - Calculate the pH of a buffered solution prepared...Ch. 15 - A buffered solution is made by adding 50.0 g NH4Cl...Ch. 15 - Calculate the pH after 0.010 mole of gaseous HCl...Ch. 15 - An aqueous solution contains dissolved C6H5NH3Cl...Ch. 15 - Calculate the mass of sodium acetate that must be...Ch. 15 - What volumes of 0.50 M HNO2 and 0.50 M NaNO2 must...Ch. 15 - Consider a solution that contains both C5H5N and...Ch. 15 - Calculate the ratio [NH3]/[NH4+] in...Ch. 15 - Carbonate buffers are important in regulating the...Ch. 15 - When a person exercises, muscle contractions...Ch. 15 - Consider the acids in Table 13-2. Which acid would...Ch. 15 - Consider the bases in Table 13-3. Which base would...Ch. 15 - Calculate the pH of a solution that is 0.40 M...Ch. 15 - Calculate the pH of a solution that is 0.20 M HOCl...Ch. 15 - Which of the following mixtures would result in...Ch. 15 - Which of the following mixtures would result in a...Ch. 15 - What quantity (moles) of NaOH must be added to 1.0...Ch. 15 - Calculate the number of moles of HCl(g) that must...Ch. 15 - Consider the titration of a generic weak acid HA...Ch. 15 - Sketch the titration curve for the titration of a...Ch. 15 - Consider the titration of 40.0 mL of 0.200 M HClO4...Ch. 15 - Consider the titration of 80.0 mL of 0.100 M...Ch. 15 - Consider the titration of 100.0 mL of 0.200 M...Ch. 15 - Consider the titration of 100.0 mL of 0.100 M...Ch. 15 - Lactic acid is a common by-product of cellular...Ch. 15 - Repeat the procedure in Exercise 61, but for the...Ch. 15 - Repeat the procedure in Exercise 61, but for the...Ch. 15 - Repeat the procedure in Exercise 61, but for the...Ch. 15 - Calculate the pH at the halfway point and at the...Ch. 15 - In the titration of 50.0 mL of 1.0 M methylamine,...Ch. 15 - You have 75.0 mL of 0.10 M HA. After adding 30.0...Ch. 15 - A student dissolves 0.0100 mole of an unknown weak...Ch. 15 - Two drops of indicator HIn (Ka = 1.0 109), where...Ch. 15 - Methyl red has the following structure: It...Ch. 15 - Potassium hydrogen phthalate, known as KHP (molar...Ch. 15 - A certain indicator HIn has a pKa of 3.00 and a...Ch. 15 - Which of the indicators in Fig. 14-8 could be used...Ch. 15 - Prob. 74ECh. 15 - Which of the indicators in Fig. 14-8 could be used...Ch. 15 - Prob. 76ECh. 15 - Estimate the pH of a solution in which bromcresol...Ch. 15 - Estimate the pH of a solution in which crystal...Ch. 15 - A solution has a pH of 7.0. What would be the...Ch. 15 - A solution has a pH of 4.5. What would be the...Ch. 15 - Derive an equation analogous to the...Ch. 15 - a. Calculate the pH of a buffered solution that is...Ch. 15 - Tris(hydroxymethyl)aminomethane, commonly called...Ch. 15 - You make 1.00 L of a buffered solution (pH = 4.00)...Ch. 15 - You have the following reagents on hand: Solids...Ch. 15 - Prob. 86AECh. 15 - Phosphate buffers are important in regulating the...Ch. 15 - What quantity (moles) of HCl(g) must be added to...Ch. 15 - Prob. 89AECh. 15 - The following plot shows the pH curves for the...Ch. 15 - Calculate the volume of 1.50 102 M NaOH that must...Ch. 15 - Prob. 92AECh. 15 - A certain acetic acid solution has pH = 2.68....Ch. 15 - A 0.210-g sample of an acid (molar mass = 192...Ch. 15 - The active ingredient in aspirin is...Ch. 15 - One method for determining the purity of aspirin...Ch. 15 - A student intends to titrate a solution of a weak...Ch. 15 - A student titrates an unknown weak acid, HA, to a...Ch. 15 - A sample of a certain monoprotic weak acid was...Ch. 15 - Consider 1.0 L of a solution that is 0.85 M HOC6H5...Ch. 15 - What concentration of NH4Cl is necessary to buffer...Ch. 15 - Consider the following acids and bases: HCO2H Ka =...Ch. 15 - Consider a buffered solution containing CH3NH3Cl...Ch. 15 - Consider the titration of 150.0 mL of 0.100 M HI...Ch. 15 - Consider the titration of 100.0 mL of 0.100 M HCN...Ch. 15 - Consider the titration of 100.0 mL of 0.200 M...Ch. 15 - Consider the following four titrations (iiv): i....Ch. 15 - Another way to treat data from a pH titration is...Ch. 15 - A buffer is made using 45.0 mL of 0.750 M HC3H5O2...Ch. 15 - A 0.400-M solution of ammonia was titrated with...Ch. 15 - What volume of 0.0100 M NaOH must be added to 1.00...Ch. 15 - Consider a solution formed by mixing 50.0 mL of...Ch. 15 - When a diprotic acid. H2A. is titrated with NaOH,...Ch. 15 - Prob. 114CPCh. 15 - The titration of Na2CO3 with HCl bas the following...Ch. 15 - Consider the titration curve in Exercise 115 for...Ch. 15 - A few drops of each of the indicators shown in the...Ch. 15 - Malonic acid (HO2CCH2CO2H) is a diprotic acid. In...Ch. 15 - A buffer solution is prepared by mixing 75.0 mL of...Ch. 15 - A 10.00-g sample of the ionic compound NaA, where...Ch. 15 - Calculate the pH of a solution prepared by mixing...Ch. 15 - Consider a solution prepared by mixing the...
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