Ch 17: Acids and Bases Flashcards
A strong acid implies ______ ________ between the H+ and A-, resulting in complete ionization.
A weak acid implies a ______ attraction between the H+ and A-, resulting in only partial ionization.
weak attraction
strong
What is meant by an “amphoteric species”?
That it can act either as an acid or a base.
p. 740
We define pH as…
And pOH as….
…the negative of the logarithm of the hydronium ion concentration:
pH = -log[H3O+]
pOH = -log[OH-]
p. 742-743
Since the pH scale is based on logarithmic function, an increase of 1 on the pH scale corresponds to….
…..a factor of 10 decrease in [H3O+].
p. 743
The log of a number is….
…the exponent to which 10 must be raised to obtain that number.
log 101 = 1
log 10-1 = -1
It is possible for concentrated acid solutions to have a ________ pH.
negative
We can use the dissociation constant for water (KW; also called the ion product constant for water) to find the [OH-] concentration when we are given [H3O+] (or vice versa) since this mathematical relationship exists:
KW = [OH-] [H3O+] = 1.0 x 10-14
p. 741
What is the mathematical relationship between pH and pOH?
pH + pOH = 14.00
p. 744
How can we calculate the pKa from the Ka value? (or vice versa)
pKa = -log [Ka]
Because strong acids, by definition, completely ionize in solution and because we can usually ignore the contribution of the autoionization of water, the concentration of H3O+ is a strong acid solution is _____ to the ____________ of the strong acid.
For example, a 0.10 M HCl solution has an [H3O+] concentration of 0.10 M and a pH of 1.00
0.10 M HCl → [H3O+] → pH = -log(0.10) = 1.00
equal to the concentration
We can define the percent ionization of a weak acid using the equation…
Percent ionization = (concentration of ionized acid/ initial concentration of acid) x 100% = [H3O+] equil / [HA]initial x 100%
The conjugate acid is a base that has….
….accepted a H+ ion.
In general, anions tend to form either ______ or neutral solutions, while cations tend to form either ______ or neutral solutions.
basic
acidic
cations - acidic or neutral
anions – basic or neutral
Remember there can be only one a in each pair, so cations must be acidic, while anions must be basic.
An anion that is the conjugate base of a weak acid is itself, a ____ ____.
weak base
An anion that is the conjugate base of a strong acid, is _________, and forms solutions that are neither acidic nor basic.
pH-neutral
In general, the weaker the acid, the stronger the conjugate base. In contrast, the conjugate base of a strong acid, such as Cl−, does not act as a base because this reaction lies far to the _____. The stronger an acid, the weaker its _________ ____.
right
conjugate base