Honors Chem II Chapter 19 Test
____________ react violently with water to form a hydroxide and hydrogen gas
alkali metals (1A) Li, Na, K, Rb, Cs, Fr
What is an indicator
an indicator is a chemical which has different colors at different pH values
what is a neutral solution
any aqueous solution in which [H+] =[OH-]
strong acids
are completely ionized in aqueous solution
weak acids
are only slightly ionized in aqueous solution (some stay together as molecules)
salt hydrolysis
chemical process where the cations or anions of a dissociated salt remove hydrogen ions from or donate hydrogen ions to water
Salt
consists of a cation (positive ion) from a base and an anion (negative ion) from an acid
Conjugate-acid base pair
consists of two substances related by the loss or gain of a single hydrogen ion
salts that produce basic solutions
contain negative ions that attract protons from water
Salts that produce acidic solutions
contain positive ions that release protons to water
Lewis base
An electron-pair donor
Bronsted Lowry Acid-base definitions
-Acid: a substance that can donate a H+ ion (proton donor) -Base: a substance that can accept a H+ ion (proton acceptor) -All arrhenius acids and bases are also acids and bases in the Bronsted-Lowry theory
What is Arrhenius' Acid-Base definition
-acids dissolve in water to produce H+ ions -Bases dissolve in water to produce OH- ions -helps explain the differences between properties
What are the limitations of Arrhenius Acid-Base theory
-restricts acids and bases to water solutions -does not include certain compounds with base properties such as NH3
The pH scale, which has a range from ________, is used to denote the _______ concentration of an ion
0 to 14; hydrogen
Properties of bases
1. tastes bitter (biting into bar of soap) 2. smooth, slippery touch 3. Can be a strong or weak electrolyte 4. Litmus paper- turns from red to blue 5. phenolphthalein indicator is pink
Properties of Acids
1. tastes sour 2. react with metals to produce hydrogen 3. can be a strong or weak electrolyte 4. litmus paper- turns from blue to red 5. phenolphthalein indicator is colorless
What are the concentrations of H+ and OH- in pure water at 25 degrees Celsius
1.0x10-7 M for both H+ and OH- at 25 degrees Celsius
The concentrations of these ions in pure water at 25 degrees Celsius are both equal to _________ mol/L
1x10^-7
Pure water at 25 degrees Celsius has a pH of ______
7
What is a Lewis acid? A Lewis Base? In what sense is the Lewis theory more general than the Arrhenius and Bronsted-Lowry theories?
A Lewis acid accepts a pair of electrons to form a covalent bond. A Lewis base donates a pair of electrons to form a covalent bond. The Lewis theory explains the behavior of compounds that act like bases without accepting hydrogen ions or that act like acids without donating hydrogen ions.
Titration
A process for determining the concentration of a solution by adding a known amount of a standard solution
Buffer
A solution in which the pH remains relatively constant when small amounts of acid or base are added
standard solution
A solution of known concentrations
Would a strong acid have a large or small Ka? Explain.
A strong acid is completely dissociated; Ka must be larger
Hydronium ion (H30+)
A water molecule that gains a hydrogen ion
Classify each compound as an Arrhenius acid or an Arrhenius base A) Ca(OH)2 B) HNO3 C) KOH D) C2H5COOH E) HBr F) H2SO4
A) base B) acid C) base D) acid E) acid F) acid
Identify each compound as a strong or weak acid or base... a. NaOH b. HCL c. NH3 d. H2SO4
A. Strong base b. Strong acid c. Weak acid d. Strong acid
Lewis acid
An electron-pair acceptor
Write a general word equation for a neutralization reaction.
Acid + base —
In the reaction of a(n) ___________ with a base, hydrogen ions and _________ ions react to produce ________
Acid; hydroxide; water
Aqueous solution of NH4Cl
Acidic
Aqueous solution of NH4NO3
Acidic
NH4Cl
Acidic
NH4NO3
Acidic
On this scale, 0 is strongly __________, 14 is strongly ________, and 7 is ________
Acidic; basic; neutral
How did Arrhenius describe acids and bases?
Acids ionize to give hydrogen ions in aqueous solution
Weak acids
Acids that are only partially ionized in aqueous solution
Monoprotic acid
Acids that contain one ionizable hydrogen
Triprotic acids
Acids that contain three ionizable hydrogens
Strong acids
Acids that ionize completely in aqueous solution
A substance that can act as both an acid and a base is called ________
Amphoteric
What group on the periodic table to like an Arrhenius base?
Any group 1A metal hydroxide
neutral solution
Aqueous solution in which [H+] and [OH-] are equal
What is the most important theory on acids and bases
Arrhenius' acid-base definitions
Alkaline solutions
Base solutions
Magnesium hydroxide and calcium hydroxide are strong _________
Bases
Strong bases
Bases that dissociate completely into metal ions and hydroxide ions in aqueous solution
Weak bases
Bases that do not dissociate completely in aqueous solution
Aqueous solution of Na2CO3
Basic
Na2CO3
Basic
NaHCO3 (sodium bicarbonate)
Basic
Solutions that resist changes in pH are called _______ solutions
Buffer
The buffer _________ is the amount of acid or base that can be added to a buffer without changing the pH greatly
Capacity
Hydrochloric acid and sulfuric acid are _______ in solution and are ________ acids
Completely; strong
A _________ is a pair of substances related by the gain or loss of a hydrogen ion
Conjugate acid-base pair
The strength of an acid or a base is determined by the __________ of the substance in solution
Degree of ionization
An acid with two ionizable hydrogen atoms is called a _________ acid
Diprotic
In the Lewis theory, an acid is an _________
Electron-pair acceptor
A Lewis base is an ________
Electron-pair donor
The __________ in an titration is the point at which the solution is neutral
End point
At the _________ point of a titration, the number of equivalents of acid equals the number of equivalents of base
Equivalence
A buffered solution cannot absorb an unlimited amount of acid or base. Explain.
Eventually the buffer capacity of the buffer is exceeded with the addition of a strong acid or base.
Examples of weak acids
HC2H3O2, H2CO3
6 strong acids
HCl, H2SO4, HNO3, HBr, HI, HCl04
An Arrhenius acid yields_________ in aqueous solution
Hydrogen ions
Salts formed from the neutralization of weak acids or weak bases _______ water. They produce solutions that are acidic or basic
Hydrolyze
The product of the concentrations of __________ ions and __________ ions in aqueous solution will always equal 1.0x10^-14
Hydronium/hydroxide; hydroxide/hydronium ions
An Arrhenius base yields _______ in aqueous solution
Hydroxide ions
The hydronium ion
In reality, the hydrogen ion (H+) is strongly attracted to the negative side of the polar water molecule
The __________ constant for water has a value of 1.0x10^-14
Ion-product
Acid Dissociation Constant (Ionization Constant)
Ka
What is the acid dissociation constant?
Ka: a quantitative measure of acid strength
what is the base dissociation constant?
Kb; weak bases have small Kb values; the weak the base, the smaller its Kb value
what is the equilibrium constant for water (Kw) for all aqueous solutions
Kw= [H+]x[OH-]=1.0x10-14 (for [H+] and [OH-], if one goes up the other goes down)
A strong acid has a much _________ Ka than a weak acid
Larger
An acid with one ionizable hydrogen atom is called a ___________ acid
Monoprotic
What is the most famous weak base?
NH3
strong bases
NaOH, KOH, RbOH, C5OH, Ca(OH)2, Sr(OH)2, Ba(OH)2
KCl
Neutral
Na2SO4
Neutral
Salts of strong acid-base reactions produce _______ solutions with water
Neutral
Salts can be _______, ______, or ______ in solutions
Neutral, acidic, basic
This reaction, called _________, is usually carried out by __________.
Neutralization; titration
Conjugate acid
Particle formed when a base gains a hydrogen ion
Conjugate base
Particle that remains when an acid has donated a hydrogen ion
End point
Point of neutralization
Ion-product constant for water (Kw)
Product of hydrogen ion and hydroxide ion concentrations for water
A Brønsted-Lowry base is a _______
Proton acceptor
A Brønsted-Lowry acid is a ______
Proton donor
acid dissociation constant (Ka)
Ratio of the contraction of the dissociated (or ionized) form of an acid to the concentration of the undissociated acid
Base dissociation constant (Kb)
Ration of concentration of conjugate acid times concentration of hydroxide ion to the concentration of conjugate base
Self-ionization
Reaction in which two water molecules produce ions
Neutralization reactions
Reactions between acids and bases to produce a salt and water
A ______ forms when an acid is neutralized by a base
Salt
What kinds of salts hydrolyze water?
Salts with cation from a weak base and an anion from a strong acid, or with a cation from a strong base and an anion from a weak acid
Water molecules can _____ to form hydrogen ions (H+) and hydroxide ions (OH-)
Self ionize
Acidic solution
Solution in which [H+] is greater than [OH-]
Basic solution
Solution in which [H+] is less than [OH-]
Concentration in solution does not affect whether an acid or a base is ________ or weak
Strong
For example, the pH of a solution at the equivalence point is greater than 7 for a _____ base-_____ acid titration
Strong; weak
Base properties
Tastes bitter and feels slippery
Acid properties
Tastes sour and will change the color of an acid-base indicator
buffer capacity
The amount of acid or base that can be added to a buffer solution before a significant change in pH can occur
Salt hydrolysis
The cations or anions of a dissociated salt remove hydrogen ions from or donate hydrogen ions to water
Why is the pH of pure water at 25 degrees Celsius equal to 7.00
The hydrogen ion concentration of pure water at 25 degrees Celcius is 10x10-7 M. The negative logarithm or pH of this concentration is 7.0
What is a characteristic of the end point of a titration?
The indicator changes color
pH
The negative logarithm of the hydrogen-ion concentration
NH4Cl
The salt produced by the titration of ammonia with hydrochloric acid
Why are Mg(OH)2 and Ca(OH)2 considered to be strong bases even though their saturated solutions are only mildly basic?
They have high Kb ratios. Their concentration in saturated solution is low because of their low solubility
Compounds can be classified as acids or bases according to ______ different theories
Three
Weak bases react with ________ to form the hydroxide ion and the conjugate _________ of the base
Water; acid
Ethanoic acid, which is only about 1 percent ionized is a ________ acid
Weak
Explain why solutions of salts that hydrolyze water do not have a pH of 7
Weak-acid anions accept protons from water, increasing the pH of the solution. Weak-base cations donate protons to water, decrease the pH
Equivalence point
When the number of moles of hydrogen ions equals the number of moles of hydroxide ions
Is it possible to have a concentrated weak acid? Explain.
Yes, acids like acetic acid dissolve well but ionize poorly
Basic (Alkaline) Solution
[H+] = [OH-]
Acidic solution
[H+] > [OH-]
what makes a buffer
a buffer is a solution of a weak acid and one of its salts or a solution of a weak base and one of its salts
what is a pH meter
a pH meter is used for precise and continuous measurements
Titration
a process of adding a known amount of solution (known concentration) to determine the concentration of another solution
buffer
a solution in which the pH remains relatively constant when small amounts of acid or base are added
Lewis acid
a substance that can accept a pair of electrons to form a covalent bond
Lewis base:
a substance that can donate a pair of electrons to form a covalent bond
Explain the self ionization of water
a very small percentage of H20 self ionizes; the reaction is in equilibrium but the arrow on top is shorter; some hydroxide ions floating around in water to make H3O
Water can act as ___________
either an acid or a base and is said to be amphoteric (a compound able to react both as a base and as an acid)
equivalence point (end point)
is reached when the moles of H+ are equal to the moles of OH-; a step in titration when it's just water and salt)
When are hydrogen atoms ionizable?
only if they are in very polar bonds
The Ka of an acid is determined from measured _________ values
pH
what is the equation to find pH
pH=-log[H+]
what does the small Ka value of a weak acid demonstrate?
small number shows us reactants are favored; also, it doesn't ionize very much
*in the examples provided for conjugate acid-base pairs, what is the difference between the acid and the base
the acid has one more H+ than the base
what can you find from titration
the molarity of an unknown concentration
How is the pH of a solution calculated?
the negative logarithm of the [H+]
Conjugate acid
the particle formed when a base gains a hydrogen ion
conjugate base
the particle that remains when an acid has donated a hydrogen ion
Standard solution
the solution of known concentration
what is the acid dissociation constant of a weak acid
weak acids have small Ka values; the weaker the acid, the smaller its Ka value
neutralization
whens acid and bases are mixed together they cancel out each other's properties and form water and an ionic compound (a salt)