Chapter 10: Acids and Bases Flashcards
An Arrhenius acid dissociates to form ____.
H+ ions
An Arrhenius base dissociates to form ____.
OH-
A Bronsted acid ____________ H+
donates
A Bronsted base ____________ H+
accepts
Bronsted-Lowry acids and bases always occur in pairs because the definitions requires what?
The transfer of a proton from the acid to the base, aka conjugate acid-base pairs
A conjugate acid is ____.
a base with a hydrogen ion added to it
in the reverse reaction, it is the H+ donor, thus it is an acid
A conjugate base is ____.
an acid with a hydrogen ion removed from it
in the reverse reaction, it accepts H+, thus it is a base.
An ____________ species is one that reacts like an acid in a basic environment and like a base in an acidic environment.
amphoteric
In the Bronsted-Lowry sense, an amphoteric species can either gain or lose a proton, making it ____________ as well
amphiprotic
The partially dissociated conjugate base of a ________________ acid is usually amphoteric, e.g. HSO4-. The ____________ of certain metals, e.g. Al, Cr, Pb, Zn, are also amphoteric.
polyvalent; hydroxides
Complex amphoteric molecules include amino acids that have a ____________ intermediate with both cationic and anionic character.
zwitterion
Acids formed from anions with names that end in -ide have the prefix ________ and the ending ____.
hydro-
-ic
Acids formed from oxyanions are called oxyacids.
If the anion ends in -ite (less oxygen), then the acid will end in ________. If the anion ends in -ate (more oxygen), then the acid will end with ____ acid.
-ous acid
-ic acid
What is the only thing that can affect Kw?
temperature! just like any other equilibrium constant
At temperatures above 298 K, Kw will increase. Why?
The autoionization reaction is endothermic
Strong acids and bases do what in aqueous solutions?
Completely dissociate
What do weak acids and bases do in aqueous solutions?
They partially dissociate
The smaller the Kb or Ka, the (stronger/weaker) a base or acid is.
weaker
Electronegative elements positioned near an acidic proton increase acid strength how?
they pull electron density out of the bond holding the acidic proton - this weakens proton bonding and facilitates dissociation
Acids and bases may react with each other to form a salt and often (not always) water. This is a ____________ reaction.
neutralization
In acid-base titrations, the equivalence point is reached when what?
the # of acid equivalents present equals the number of base equivalents, or vice versa
THe point at which the indicator changes to its final color is not the equivalence point, but rather the ____________
endpoint
Main differences between strong acid vs weak acid titration with strong base?
- initial pH is greater
- strong acid has steeper/sudden rise in pH
- equivalence point is greater than 7
Why do weak acid strong base titrations have pH > 7?
produces a weak conjugate base and even weaker conjugate acid - this means there are more OH- than H3O+
A ____________ ____________ consists of a mixture of a weak acid and its salt (which is composed of its conjugate base and a cation) OR a mixture of a weak base and its salt.
buffer solution
What are two major examples of buffers?
CH3COOH and CH3COO-Na+
NH3 and NH4+Cl-
What is an important property of buffers?
Can resist changes in pH when small amounts of acid or base are added
One of the most important buffers in the human body is the ________________ buffer system.
bicarbonate
In metabolic acidosis, what occurs?
Increased breathing to deplete CO2 and shift the system to the left to reduce H+
What would happen if concentrations of both the acid and its conjugate base were doubled in a buffer solution?
THe buffering capacity, or ability to which the system can resist changes in pH, would increase
Oxidation is ________
loss of e-
Reduction is ________
gain of e-
An oxidizing agent causes what?
Causes an atom to be oxidized, and is itself reduced
A reducing agent causes what?
Causes an atom to be reduced, and is itself oxidized
Almost all oxidizing agents contain what?
oxygen or another strongly electronegative element
What are some common oxidizing/reducing agents?
________________ ____________ are assigned to atoms to keep track of redistribution of electrons during chemical reactions
Oxidation numbers
What is the oxidation number of a free element?
Zero
The oxidation number of a monatomic ion is equal to what?
The charge of the ion
The oxidation number of Group VIIA is -1, except for when?
When combined with an element of higher electronegative.
Example: Cl- is -1 in HCl, but it is +1 in HOCl
Hydrogen is usually ____. However, it is ____ in compounds with less electronegative elements from Groups ____ and ____.
Hydrogen is ____ in HCl, but ____ in NaH.
+1; -1; Groups IA and IIA
+1, -1
In most compounds, the oxidation number of oxygen is ____. Except in peroxides (O22-), where oxygen is ____, and compounds with more electronegative elements like OF2, where oxygen is ____.
-2; -1, +2
The sum of oxdiation numbers in a neutral compound should be ____
zero
The sum of oxidation numbers of the atoms present in a polyatomic ion is equal to ____
the charge of the ion
Oxidation number assumes ________ ________ of electrons in bonds, “awarding” the electrons to the more electronegative element.
unequal division
Formal charge assumes ________ ________ of electrons in bonds, awarding one electron to each atom in the bond.
equal division
When assigning oxidation numbers, start with what?
The known atoms
What does assigning oxidation numbers accomplish?
Allows us to determine how many moles of each species are required for conservation of charge and mass, which is necessary to balance the equation
How does the half-reaction method work?
Separate the redox reaction into two half-reactions, the oxidation part and the reduction part, then they are balanced separately
________________ is a specific type of redox reaction in which an element undergoes both oxidation and reduction in producing its products.
disproportionation
What is an example of disproportionation?
catalysis of peroxides by catalase
