How do you find the pH of a solution with an acid and a conjugate base?

When the moles of base added equals half the total moles of acid, the weak acid and its conjugate base are in equal amounts. The ratio of CB / WA = 1 and according to the HH equation, pH = pKa + log(1) or pH = pKa.

What is the pH of a buffer solution when its weak acid and conjugate base components are in equal concentrations?

A solution that contains a weak acid and its conjugate base in comparable amounts, not necessarily in equal amounts, is called a buffer solution. As you can see here, equal amounts of weak acid and of conjugate base will make the log term equal to zero, and thus the pH equal to the pKa .

What is the pH range of a buffer?

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.

What are buffer solutions give an example for acidic buffer?

Acidic buffers are solutions that have a pH below 7 and contain a weak acid and one of its salts. For example, a mixture of acetic acid and sodium acetate acts as a buffer solution with a pH of about 4.75.

What equation is used for calculating the pH of an acid buffer?

The formula for the Henderson–Hasselbalch equation is: pH=pKa+log([A−][HA]) pH = p K a + log ( [ A − ] [ HA ] ) , where pH is the concentration of [H+], pKa is the acid dissociation constant, and [A–] and [HA] are concentrations of the conjugate base and starting acid.

Why buffer capacity is greatest pH pKa?

The value of the buffer capacity is strongly related to the concentrations of ingredients used and increases with their increase. Buffer solutions with a pH equal to the pKa value of the acid (used to make this solution) have the greatest buffering capacity.

Why does a buffer work best at a pH near its pKa?

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.

How does a pH buffer work?

Buffers work by neutralizing any added acid (H+ ions) or base (OH- ions) to maintain the moderate pH, making them a weaker acid or base. Now, because all the extra H+ ions are locked up and have formed a weaker acid, NH4+, thus the pH of the system does not change significantly.