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Chapter 14
Acids and Bases

14-03-01a
Title
Spacefilling model of hydrochloric acid
Caption
Hydrogen is present as an H+ ion.
Notes
HCl is a very common acid, used to clean metals, prepare and process some foods, and refine metal ores. Some might know this as muriatic acid.
Keywords
acid, hydrochloric acid
14-03-02b
Title
Spacefilling model of sulfuric acid
Caption
Hydrogen is present as an H+ ion.
Notes
H2SO4 is a very common acid, used in laboratories and in the manufacture of fertilizers, explosives, dyes, and glue. It is also used in automobile batteries.
Keywords
acid, sulfuric acid
14-03-03c
Title
Spacefilling model of nitric acid
Caption
Hydrogen is present as an H+ ion.
Notes
HNO3 is a very common acid, used in laboratories and in the manufacture of fertilizers, explosives, dyes, and glue.
Keywords
acid, nitric acid
14-03-04d
Title
Spacefilling model of acetic acid
Caption
Hydrogen is present as an H+ ion.
Notes
HC2H3O2 is a very common acid, found in vinegar. It is a carboxylic acid, possessing the characteristic -COOH group. It is derived from organic sources.
Keywords
acid, acetic acid, carboxylic acid, organic
14-03-06f
Title
Spacefilling model of carboxylic acid group
Caption
Hydrogen is present as an H+ ion.
Notes
The -COOH group is present in all carboxylic acids. Carboxylic acids are derived from organic sources.
Keywords
acid, carboxylic acid, organic
14-03-07g
Title
Spacefilling models of citric acid and malic acid
Caption
Hydrogen is present as an H+ ion. Note that not all of the hydrogens in these molecules are present as ions: Most are bonded to carbon atoms through ordinary covalent bonds.
Notes
Citric acid and malic acid are common acids, found in fruits: citric acid in citrus fruits, and malic acid in apples, grapes, and wine.
Keywords
acid, citric acid, malic acid, carboxylic acid, organic
14-05
Title
HCl is a strong electrolyte
Caption
The Arrhenius definition of an acid is a substance that produces H+ ions in solution. We will see later that these H+ ions associate with H2O to form H3O+ ions.
Notes
The HCl molecule dissociates in water to produce the H+ and Cl- ions. The H+ ions associate with H2O to form H3O+ ions. HCl is a strong acid, because the acid is 100% dissociated in water.
Keywords
acid, hydrochloric acid, hydronium, strong electrolyte, Arrhenius
14-05-01un
Title
Lewis dot structures for hydronium ion formation
Caption
The H+ ions associate with H2O to form H3O+ ions. HCl is a strong acid, because the acid is 100% dissociated in water.
Notes
The Arrhenius definition of an acid is a substance that produces H+ ions in solution. The H+ ions are so small they are readily attracted to a lone pair on water. The resulting polyatomic ion, called a hydronium ion, satisfies oxygen's octet and the duets of all three hydrogens.
Keywords
acid, hydrochloric acid, hydronium, water, hydrogen ion
14-06
Title
NaOH is a strong electrolyte
Caption
The Arrhenius definition of a base is a substance that produces OH- ions in solution.
Notes
The NaOH molecule dissociates in water to produce the Na+ and OH- ions. NaOH is a strong base, because the base is 100% dissociated in water.
Keywords
base, sodium hydroxide, strong electrolyte, Arrhenius
14-07
Title
Conjugate acid–base pairs
Caption
A conjugate acid–base pair is any two substances related to each other by the transfer of a proton.
Notes
According to the BrŅnsted-Lowry definition, the acid is the proton donor; the base is the proton acceptor. In these examples, H2O and NH4+ would be the acids; NH3 and OH- would be the bases.
Keywords
BrŅnsted-Lowry, proton, acid, base, conjugate acid–base pair
14-07-01un
Title
Conjugate acid–base pair equation
Caption
A conjugate acid–base pair is any two substances related to each other by the transfer of a proton. Here, water transfers a proton to an ammonia molecule.
Notes
According to the BrŅnsted-Lowry definition, the acid is the proton donor; the base is the proton acceptor.
Keywords
BrŅnsted-Lowry, proton, acid, base, conjugate acid–base pair
14-07-02un
Title
Conjugate acid–base pair equation: Example 14.1a
Caption
A conjugate acid–base pair is any two substances related to each other by the transfer of a proton. Here, sulfuric acid transfers a proton to a water molecule.
Notes
According to the BrŅnsted-Lowry definition, the acid is the proton donor; the base is the proton acceptor.
Keywords
BrŅnsted-Lowry, proton, acid, base, conjugate acid–base pair
14-07-03un
Title
Conjugate acid–base pair equation: Example 14.1b
Caption
A conjugate acid–base pair is any two substances related to each other by the transfer of a proton. Here, water transfers a proton to a bicarbonate ion.
Notes
According to the BrŅnsted-Lowry definition, the acid is the proton donor; the base is the proton acceptor.
Keywords
BrŅnsted-Lowry, proton, acid, base, conjugate acid–base pair
14-07-04un
Title
General pattern for acid–base neutralization
Caption
An acid–base neutralization generally follows the pattern shown. This is one of the most important acid–base reactions.
Notes
The net ionic equation is: H+ + OH- --> H2O
Keywords
proton, acid, base, salt, water, neutralization
14-07-10un
Title
Multistep solution map for converting mL of an NaOH solution to grams HCl
Caption
The stated factors use a metric conversion, the given molarity of the NaOH solution, and the balanced reaction equation to make the conversion. The 1:1 factor arises from the balanced equation.
Notes
The factors can be adapted to any similar mL-grams conversion.
Keywords
mole, chemical formula, molarity, balanced equation, neutralization, acid, base
14-07-11un
Title
Solution map for calculating molarity
Caption
The stated factor uses the moles of HCl and volume of the HCl solution in liters.
Notes
This factor can be adapted to any molarity determination.
Keywords
mole, molarity, acid
14-07-12un
Title
Dissociation of a strong acid
Caption
When a strong acid dissociates, 100% of the molecules give up the H+ ion. The single arrow in the reaction equation indicates that 100% dissociation occurs.
Notes
The single arrow indicates complete ionization of the acid.
Keywords
acid, ionization, dissociation, hydrochloric acid, hydronium ion
14-08
Title
HCl in water undergoes complete ionization
Caption
When HCl dissolves in water, it completely ionizes into H3O+ and Cl-. The solution contains no intact HCl. HCl is therefore a strong electrolyte.
Notes
The H+ ions join with water molecules to form hydronium ions.
Keywords
acid, ionization, dissociation, hydrochloric acid, hydronium ion, strong electrolyte
14-09-01un
Title
Dissociation of a weak acid
Caption
When a weak acid dissociates, less than 100% of the molecules give up the H+ ion. The double arrow in the reaction equation indicates that incomplete dissociation occurs.
Notes
The double arrow indicates incomplete ionization of the acid. One way of looking at it is to imagine acid molecules ionizing at the same time that ions are reconstituting themselves into undissociated acid molecules. The result is that the solution will never have all acid molecules dissociated.
Keywords
acid, ionization, dissociation, hydrofluoric acid, hydronium ion
14-10
Title
HF in water undergoes incomplete ionization
Caption
When HF dissolves in water, only a fraction of the dissolved molecules ionize into H3O+ and F- ions. The solution contains many intact HF molecules.
Notes
The H+ ions join with water molecules to form hydronium ions.
Keywords
acid, ionization, dissociation, hydrofluoric acid, hydronium ion, weak electrolyte
14-12
Title
Strong and weak acids
Caption
a) In a strong acid, the attraction between H+ and A- is low, resulting in complete ionization. b) In a weak acid, the attraction between H+ and A- is high, resulting in partial ionization.
Notes
Another interpretation states that the strong acid is a primarily ionic compound, but the weak acid has significant covalent character.
Keywords
acid, ionization, dissociation, weak electrolyte, strong electrolyte
14-13
Title
NaOH in water undergoes complete ionization
Caption
When NaOH dissolves in water, it completely dissociates into Na+ and OH-. The solution contains no intact NaOH. Would NaOH be a strong or weak electrolyte?
Notes
When NaOH dissolves in water, it completely ionizes into Na+ and OH-. The solution contains no intact NaOH. NaOH is therefore a strong electrolyte.
Keywords
base, ionization, dissociation, sodium hydroxide, strong electrolyte
14-14
Title
Ammonia in water undergoes incomplete ionization
Caption
When NH3 dissolves in water, it partially ionizes to form NH4+ and OH-. However, only a fraction of the molecules ionize. Most NH3 molecules remain as NH3. Would NH3 be a strong or weak electrolyte?
Notes
When NH3 dissolves in water, only a fraction of the dissolved molecules ionize with water to form NH4+ and OH-. The solution contains many intact NH3 molecules. Ammonia is a weak electrolyte.
Keywords
base, ionization, dissociation, ammonia, hydroxide ion, ammonium ion, weak electrolyte
14-14-01un
Title
Water acts as both an acid and a base
Caption
Water can accept protons from an acid to form hydronium ion. But water can also provide protons to a base to form hydroxide ions. When only water is present, water acts as both an acid and a base, in a process called self-ionization: H2O + H2O --> H3O+ + OH-
Notes
Water is a very weak acid and a very weak base. Whether water acts as an acid or base depends on what other species is present.
Keywords
acid, base, amphoteric, water, self-ionization
14-14-02un
Title
Water is amphoteric
Caption
Water can accept protons from an acid to form hydronium ion. But water can also provide protons to a base to form hydroxide ions. When only water is present, water acts as both an acid and a base, in a process called self-ionization: H2O + H2O --> H3O+ + OH-
Notes
Water is a very weak acid and a very weak base. Whether water acts as an acid or base depends on what other species is present.
Keywords
acid, base, amphoteric, water, self-ionization
14-14-03un
Title
Logarithms and significant figures
Caption
Only the numbers to the right of the decimal place are significant in a logarithm. This makes sense, because a logarithm expresses the power of 10 that corresponds to a measurement.
Notes
In this example, the measurement 1.0 x 10-3 has two significant figures. Therefore, the logarithm should be expressed to two places to the right of the decimal.
Keywords
pH, logarithm, significant figures
14-14-04un
Title
Logarithms and significant figures
Caption
Only the numbers to the right of the decimal place are significant in a logarithm. This makes sense, because a logarithm expresses the power of 10 that corresponds to a measurement.
Notes
In this example, the measurement 1.00 x 10-3 has three significant figures. Therefore, the logarithm should be expressed to three places to the right of the decimal.
Keywords
pH, logarithm, significant figures
14-14-05o
Title
pH scale
Caption
The pH is a unit defined to express the acidity of solutions. The more acidic the substance, the lower its pH.
Notes
pH was defined in order to express very widely ranging hydronium ion concentrations in a scale that we can easily understand.
Keywords
pH, logarithm, molarity
14-15
Title
The pH scale as a logarithmic scale
Caption
The pH scale is a logarithmic scale. A decrease of 1 unit on the pH scale corresponds to an increase of 10 in H3O+ concentration. How much of an increase in H3O+ concentration corresponds to a decrease of 2 pH units?
Notes
Each pH unit corresponds to a power of ten in the hydronium ion concentration. Therefore, a decrease of two pH units would be a 100-fold increase in hydronium ion concentration.
Keywords
pH, logarithm, molarity
14-17
Title
Buffer systems
Caption
A buffer contains significant amounts of a weak acid and its conjugate base. The acid consumes any added base, and the base consumes any added acid. In this way, a buffer resists pH change.
Notes
Buffers are found in blood and other biological systems, in which a narrow, constant pH range is necessary for proper function.
Keywords
buffer, acid, base, conjugate base, weak acid, neutralization, pH
14-18
Title
Map of pH of precipitation in the U.S.
Caption
Average pH of precipitation in the United States for the period 12/25/2000 to 1/1/2001. Low pH values can correspond to environmental damage.
Notes
The map contains values from the National Atmospheric Deposition Program.
Keywords
acid, base, neutralization, pH, acid rain, environment
14-20
Title
1980–1997 SO2 emissions from utilities
Caption
1980 to 1997 SO2 emissions from utilities. The height of each bar represents annual SO2 emissions for that region in the year noted. Under the Clean Air Act and its amendments, SO2 emissions are decreasing in most parts of the country.
Notes
SO2 contributes to acid rain because it is readily converted to sulfuric acid in the atmosphere.
Keywords
sulfur dioxide, sulfuric acid, acid rain, Clean Air Act
14-20-01un
Title
Multistep solution map for converting mL H2SO4 to moles NaOH
Caption
The stated factors use a metric conversion, the given molarity of the H2SO4 solution, and the balanced reaction equation to make the conversion. The 2:1 factor arises from the balanced equation.
Notes
The factors can be adapted to any similar mL-moles conversion.
Keywords
mole, chemical formula, molarity, balanced equation, neutralization, acid, base
14-20-02p
Title
HF is a weak acid
Caption
When HF dissolves in water, only a fraction of the dissolved molecules ionize into H3O+ and F-. The solution contains many intact HF molecules.
Notes
The H+ ions join with water molecules to form hydronium ions.
Keywords
acid, ionization, dissociation, hydrofluoric acid, hydronium ion, weak electrolyte
14-20-03q
Title
HI is a strong acid
Caption
When HI dissolves in water, it completely ionizes into H3O+ and I-. The solution contains no intact HI. HI is therefore a strong electrolyte.
Notes
The H+ ions join with water molecules to form hydronium ions.
Keywords
acid, ionization, dissociation, hydroiodic acid, hydronium ion, strong electrolyte
14-20-04r
Title
HCHO2 is a weak acid
Caption
When HCHO2 dissolves in water, only a fraction of the dissolved molecules ionize into H3O+ and CHO2-. The solution contains many intact HCHO2 molecules.
Notes
The H+ ions join with water molecules to form hydronium ions.
Keywords
acid, ionization, dissociation, oxalic acid, hydronium ion, weak electrolyte
14-20-05s
Title
HNO3 is a strong acid
Caption
When HNO3 dissolves in water, it completely ionizes into H3O+ and NO3-. The solution contains no intact HNO3. HNO3 is therefore a strong electrolyte.
Notes
The H+ ions join with water molecules to form hydronium ions.
Keywords
acid, ionization, dissociation, nitric acid, hydronium ion, strong electrolyte
14-20-07un
Title
Solution map for calculating molarity
Caption
The stated factor uses the moles of NaOH and volume of the NaOH solution in liters.
Notes
This factor can be adapted to any molarity determination.
Keywords
mole, molarity, base

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