Why is a buffer said to be the most efficient when its pH pKa?

The capacity of a buffer solution to keep at nearly constant pH when a small amount of base or acid is added to the solution is greatest at the pKa and diminishes as the pH of the solution goes below or above the pKa.

What happens when pH and pKa are equal?

A solution to this equation is obtained by setting pH = pKa. This means that when the pH is equal to the pKa there are equal amounts of protonated and deprotonated forms of the acid. For example, if the pKa of the acid is 4.75, at a pH of 4.75 that acid will exist as 50\% protonated and 50\% deprotonated.

When the pH of buffer is equal to its pKa then?

Based on the Henderson-Hasselbalch equation, it can be seen that the pH of the buffer solution is equal to the pKa value of the acid, when the ratio of undissociated acid concentration to the anion concentration (resulting from the dissociation of this acid) equals 1, because log(1) = 0.

What is the relationship between the pH of a buffer and the pKa of the acid used to make it why?

The lower the pH, the higher the concentration of hydrogen ions [H+]. The lower the pKa, the stronger the acid and the greater its ability to donate protons. pH depends on the concentration of the solution. This is important because it means a weak acid could actually have a lower pH than a diluted strong acid.

Why does a buffer work best when the pH of the buffered solution is close to the pKa of the acid used to make the buffer?

A buffer works best when there is the same amount of weak acid/base and its conjugate. If you look at the Henderson Hasselbalch equation, and set the concentration of the weak acid/base equal to each other, pH=pKa.

At what pH does a buffer work best?

Buffers are generally good over the range pH = pKa ± 1. The ammonia buffer would be effective between pH = 8.24 – 10.24. The acetate buffer would be effective of the pH range from about 3.74 to 5.74. Outside of these ranges, the solution can no longer resist changes in pH by added strong acids or bases.

Why does pH equal pKa?

At the half-equivalence point, the acid is half neutralized, hence produced salt is half in amount than that of acid i.e. concentration of salt and acid are same ]. This solution now becomes a buffer solution and applying Henderson-Hasselbalch equation, the log value becomes zero. So, pH=pKa at half-equivalence point.

Is pH equal to pKa at equivalence point?

At the half-equivalence point, pH = pKa when titrating a weak acid. After the equivalence point, the stoichiometric reaction has neutralized all the sample, and the pH depends on how much excess titrant has been added. After equivalence point, any excess strong base KOH determines the pH.

Why do buffers have a pH range?

A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or base, thus maintaining the pH of the solution relatively stable. This is important for processes and/or reactions which require specific and stable pH ranges.

Why does buffer capacity increase with concentration?

A higher buffer concentration has a greater buffer capacity. This means that a greater amount of hydrogen ions, or a stronger acid, would have to be added to disrupt the equilibrium and change the pH of the buffer. Buffer capacity is also affected by the relative concentrations of the buffer components.

What makes a buffer a good buffer?

Buffers essentially maintain pH for a system. The effective buffering range of a buffer is a factor of its pKa, the dissociation constant of the weak acid in the buffering system. Many things, such as changes in temperature or concentration, can affect the pKa of a buffer.