Water will react most completely as an acid with
A. SO3^-2
B. H2BO3-
C. C6H5O-
D. CH3COO-
Why isn't the answer A, since
H2O + SO3^-2 <-> HSO3- + OH-
so H2O and HSO3- are the conjugate acids.
What you say is true but that isn't the question. A, B, C, AND D (ALL OF THEM) are bases and ALL will react with H2O to produce acids. The question is which ONE does this more completely.
Oh, so they're all bases. Is the answer C because it is the strongest base out of the four. Does the stronger the base mean the more reaction? Thanks.
I can't read the small number in my text but it appears that phenol (C6H5OH) is the smallest which would make Kb the largest. What it means is, we write the equilibrium for the reaction with water as
A^- + HOH ==> HA + OH^-
Kb = Kw/Ka = (HA)(OH^-)/(HA)
So a large Kb means HA and OH are large and HA is small and that means the reaction occurs to a larger extent than for a small Kb. (Remember the discussions you have had about the reaction quotient).
Thank you so much for the clarification!
To determine which species water will react most completely as an acid with, we need to identify the species that water can donate a proton (H+) to. The reaction you mentioned between water (H2O) and sulfite ion (SO3^2-) does occur, but it does not necessarily mean that water will react most effectively as an acid with sulfite ion.
The reaction between water and sulfite ion involves the transfer of a proton from water to sulfite ion, forming bisulfite ion (HSO3-) and hydroxide ion (OH-), as you correctly mentioned:
H2O + SO3^2- ⇌ HSO3^- + OH-
However, for water to act as an acid, it needs to donate a proton (H+). In this case, water donates its proton to the sulfite ion, making water the Brønsted-Lowry acid, and sulfite ion the Brønsted-Lowry base.
To determine which species water will react most completely as an acid with, we need to identify the species that is a stronger base than sulfite ion. In other words, we are looking for a species that can better accept the proton from water.
Among the given options, the strongest base is the one that is most likely to accept a proton. The stronger the conjugate base, the more likely water will react completely as an acid. Let's analyze each option:
A. SO3^2- (sulfite ion) - Sulfite ion is a weak base, and it can accept a proton from water. However, the other options may be stronger bases.
B. H2BO3^- (hydrogen borate ion) - Hydrogen borate ion is the conjugate base of boric acid (H3BO3), and it is relatively weak. It can accept a proton from water, but other options might be stronger bases.
C. C6H5O^- (phenoxide ion) - Phenoxide ion is the conjugate base of phenol (C6H5OH). It is a moderate base, but other options could be stronger.
D. CH3COO^- (acetate ion) - Acetate ion is the conjugate base of acetic acid (CH3COOH). It is a weak base but stronger than the other options mentioned above.
Therefore, the correct answer is D. CH3COO^-, as it is the strongest base among the given options and more likely to react completely with water as an acid.