8 - Acids and Bases Flashcards
Arrhenius theory
in an aqueous solution, an acid is a substance that produces hydrogen ions and a base is a substance that produces hydroxide ions
Bronsted-Lowry theory
an acid is a hydrogen ion (proton) donor and a base is a hydrogen ion (proton) acceptor, accounts for bases without OH-
conjugate acid
the substance that forms when a base, according to the Bronsted Lowry theory, accpets a hydrogen ion (proton)
conjugate base
the substnace that forms when an acid loses a hydrogen ion (proton)
conjugate acid-base pair
two substances related to each other by the donating an accepting of a single hydrogen ion
amphiprotic (amphoteric)
able to donate or accept a hydrogen ion (proton) and thus acr as both a Bronsted-Lowry acid and a Bronsted-Lowry base
acid ionization contant (Ka)
equilibrium contant for the ionization of an acid; also called the acid of dissociation contant
strong acid
an acid that ionizes almost 100 percent in water, producing hydrogen ions
weak acid
an acid that only partly ionizes
organic acid
an acid (expcept carbonic acid) containing carbon, oxygen, and hydrogen atoms, also called carboxylic acid
strong base
a base that dissociated completley in water, producing hydroxide ions
weak base
a base that only partially reacts with water to produce hydroxide ions
base ionization constant
the equilibrium constant for the ionization of a base; also called the base dissociation constant
organic base
an organic compound that increases the concentration of hydroxide ions in aqueous solution
autoionization of water
the transfer of a hydrogen ion from one water molecule to another
ion-product constant for water
the equilibrium consrtant for the autoionization of water
pH meter
a devide that measures the acidity or alkalinity of a solution electronically and displays the result as a pH value
monoprotic acid
an acid that possess only one ionizable (acidic) hydrogen atom
polyprotic acid
an acid that possesses more than one ionizable (acidic) hydrogen atom
sample
The solution being analyzed in a titration, which is placed in a receiving
flask (Erlenmeyer flask). The volume is known, but the concentration
is usually unknown.
titrant
The solution in the burette during the titration. Concentration of the
titrant is known, and the titrant is added to the sample. The volume of
the titrant needed to neutralize the sample is recorded and used to
calculate the concentration of the sample. If the sample is a base, the
titrant used is an acid, and vice versa.
standard solution
A solution whose concentration is accurately and precisely known. Made
by dissolving a primary standard in distilled water.
primary standard
A highly pure and stable chemical used to determine the precise
concentration of acids or bases (used to test the accurate concentration
of the titrant). Common primary standards include sodium carbonate,
Na2CO3(s) and potassium hydrogen phthalate, KHC8H4O4(s).
Equivalence Point
The point in a titration when neutralization is complete. At this
point, all the reactant in the sample is used up. (na = nb)
In problems, this is the empirically determined point.
Endpoint
The point in a titration at which a sharp change in a measurable
and characteristic property occurs, usually a colour change.
Indicator
A solution of a weak acid or base that changes colour at a
certain pH, “indicating” when the equivalence point is reached
and titration is complete.
Ex) Phenolphthalein for bases, and Methyl Orange for acids
pH curve
A graph of pH plotted against volume of titrant added in an
acid-base titration. The centre of the vertical region of the pH
curve indicates the equivalence point. Also known as a titration
curve.
