The buffer capacity of a solution is a measure of the amount of acid or base that the solution can absorb without a significant change in pH. What are the concentration of NH3 (aq) and NH4+ (aq) that will produce the maximum buffer capacity?
(Base dissociation constant Kb=1.8x10^-5 mol dm^-3)
A 0.1 0.2
B 0.5 0.5
C 1.0 2.0
D 2.0 1.0
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Answers & Comments
The maximum buffer capacity occurs when the ratio of salt to acid is 1:1, so in this example, it would be 0.5, 0.5, or (B).
whilst a sturdy base is further to a buffer answer, the pH of the answer will enhance. genuine. extreme pH potential project-unfastened because of the fact this is a adverse log scale. The buffer purely prevents the pH from changing plenty. it is going to nonetheless circulate up if a sturdy base is further. whilst NH4+ is further to an ammonia answer (NH3), the pH of the answer decreases. genuine. NH4+ is a sturdy acid. low pH is acidic. whilst NaCH3COO is further to an acetic acid answer (CH3COOH), the pH of the answer will enhance. genuine. acetic acid is a (somewhat) vulnerable acid, usually forming dimers somewhat than dissociating. Na- CH3COO+ is a stong base . This will enhance the pH. The pH of an NH4+/NH3 buffer is 9. which means [NH3] > [NH4+]. [Kb(NH3) = a million.8 × 10-5] Flase. pKa = 9.3 so which you like extra acid to get all the way down to 9 a typical buffer is composed of a vulnerable acid and a vulnerable base that are a conjugate acid/base pair. fake. A vulnerable acid will kind a conjugate sturdy acid. vise versa. you are able to't have vulnerable acid/vulnerable base conjugate pairs. The pH of an HF/KF buffer is 3. which means [HF] < [KF]. [Ka(HF) = 7.a million × 10-4] fake. pKa = 3.15 so which you like extra so which you like extra acid to get all the way down to 3. pKa = -log10(Ka) Ka = 10^-14 / Kb pH = pKa + log( [Base]/[Acid])