Chapter 16 (sections 1-3) Flashcards
Define buffer
A solution containing significant amounts of both a weak acid and its conjugate base (or a weak base and its conjugate acid) that resists pH change by neutralizing added acid or added base
A buffer resists pH change by _____ added acid or base.
neutralizing
A buffer contains significant amounts of …?
both a weak acid AND its conjugate base (or a weak base and its conjugate acid)
Buffers ____ pH change.
resist
A____ contains significant amounts of both a weak acid and its conjugate base
buffer
In a buffer the weak acid ____ added base until the concentration of the base…?
neutralizes
exceeds the concentration of the weak acid
In a buffer, the conjugate base ____ the added acid until the concentration of the acid …?
neutralizes
exceeds the concentration of the conjugate base
Define common ion affect
The tendency for a common ion to decrease the solubility of an ionic compound or to decrease the ionization of a weak acid or weak base
Using the approximation that x is small we can consider the equilibrium concentrationd of HA and A- to be essentially …?
identical to the initial concentrations of HA and A-
To determine the concentration of [H₃0⁺] for any buffer solution, we…?
multiply Ka by the ratio of the concentrations of the acid and the conjugate base
[H₃0⁺] = Ka [HA]/[A⁻]
In a buffer solution where the concentrations of the acid and conjugate base are equal what is [H₃0⁺] equal to?
Ka
When calculating the pH of a buffer, adding a small amount of strong acid to a buffer converts the stoichiometric amount of the _____ to the _____ ____
base
conjugate acid
When calculating the pH of a buffer, adding a small amount of strong base to a buffer converts the stoichiometric amount of the _____ to the _____ ____
acid
conjugate base
Define buffering action
The way a buffer solution reacts with small amounts of acid or base to maintain a fairly constant pH
pKa + pKb =..?
14
When is a buffer most effective?
When the concentrations of the acid and conjugate base are equal
A buffer becomes less effective as the difference in relative amounts of acid and conjugate base ______.
Increases
In order for a buffer to be reasonably effective, the relative concentrations of acid and conjugate base should not differ by more than a factor of _____.
10
A buffer is most effective (most resistant to pH changes) when the concentrations of acid and conjugate base are ____.
high
Lowest pH for effective buffers occurs when the base is one-tenth as concentrated as the acid. What is this in equation format?
pH = pKa -1
Highest pH for effective buffer occurs when the base is 10 times as concentrated as the acid. What is this in equation format?
pH = pKa + 1
The effective range for a buffering system is…?
one pH unit on either side of the pKa
Define buffer capacity
the amount of acid or base that can be added to a buffer without destroying its effectiveness
The buffer capacity increases with ____ absolute concentrations of the buffer components
increasing
Overall buffer capacity increases as the relative concentrations of the buffer components become…?
more similar to each other
As the ratio of the buffer components gets closer to one, the overall capacity of the buffer becomes _____.
greater
