buffers

(noun)

A weak acid or base used to maintain the acidity (pH) of a solution near a chosen value and which prevent a rapid change in pH when acids or bases are added to the solution.

Related Terms

Examples of buffers in the following topics:

  • Buffer Range and Capacity

    • A buffer's capacity is the pH range where it works as an effective buffer, preventing large changes in pH upon addition of an acid or base.
    • A titration curve visually demonstrates buffer capacity.
    • This is the buffer zone.
    • However, once the curve extends out of the buffer region, it will increase tremendously when a small amount of acid or base added to the buffer system.
    • Discuss correlation between the pKa of the conjugate acid of a buffer solution and the effective range of the corresponding buffer.

  • Calculating Changes in a Buffer Solution

    • The changed pH of a buffer solution in response to the addition of an acid or a base can be calculated.
    • These solutions are known as buffers.
    • What would be the pH of the sodium hydroxide solution without the buffer?
    • Solving for the buffer pH after 0.0020 M NaOH has been added:
    • It also shows the importance of using high buffer component concentrations so that the buffering capacity of the solution is not exceeded.

  • Preparing a Buffer Solution with a Specific pH

    • For example, blood in the human body is a buffer solution.
    • Buffer solutions are necessary in a wide range of applications.
    • There are a couple of ways to prepare a buffer solution of a specific pH.
    • Both solutions must contain the same buffer concentration as the concentration of the buffer in the final solution.
    • To get the final buffer, add one solution to the other while monitoring the pH.

  • Relative Amounts of Acid and Base

    • A buffer's pH changes very little when a small amount of strong acid or base is added to it.
    • Suppose you wish to prepare a buffer solution to keep the pH at 4.30.
    • What amount of acid and base should you use to create the buffer?
    • This is due to the change that occurs when another acid or base is added to the buffer.
    • The more the ratio needs to differ to achieve the desired pH, the less effective the buffer.

  • Absolute Concentrations of the Acid and Conjugate Base

    • A buffer's pH changes very little when a small amount of strong acid or base is added to it.
    • A concentrated buffer can neutralize more added acid or base than a dilute buffer, because it contains more acid/conjugate base.
    • However, any buffer will lose its effectiveness if too much strong acid or base is added.
    • Therefore, the pH for the buffer with an acid/base concentration of 0.7/0.6M is 4.68.
    • Therefore, the pH of the weaker buffer before the addition of HCl is the same.

  • Calculating the pH of a Buffer Solution

    • The pH of a buffer can be calculated from the concentrations of the various components of the reaction.
    • The balanced equation for a buffer is:
    • Calculate the pH of a buffer solution that initially consists of 0.0500 M NH3 and 0.0350 M NH4+.
    • ICE table for the buffer solution of NH4+ and NH3 with the starting concentrations.
    • Calculate the pH of a buffer made only from a weak acid.

  • The Henderson-Hasselbalch Equation

    • The equation is also useful for estimating the pH of a buffer solution and finding the equilibrium pH in an acid-base reaction.
    • The equation can be derived from the formula of pKa for a weak acid or buffer.
    • An example of how to use the Henderson-Hasselbalch equation to solve for the pH of a buffer solution is as follows:
    • What is the pH of a buffer solution consisting of 0.0350 M NH3 and 0.0500 M NH4+ (Ka for NH4+ is 5.6 x 10-10)?
    • Calculate the pH of a buffer system using the Henderson-Hasselbalch equation.

  • Buffers Containing a Base and Conjugate Acid

    • An alkaline buffer can be made from a mixture of the base and its conjugate acid, but the formulas for determining pH take a different form.
    • An alkaline buffer can be made from a mixture of a base and its conjugate acid, similar to the way in which weak acids and their conjugate bases can be used to make a buffer.
    • Calculate the pH of a buffer solution consisting of 0.051 M NH3 and 0.037 M NH4+.
    • Calculate the pH of an alkaline buffer system consisting of a weak base and its conjugate acid.

  • The Common Ion Effect

    • A buffer solution is composed of a weak acid and its conjugate base, or a weak base and its conjugate acid.
    • Addition of excess ions will alter the pH of the buffer solution.
    • In the case of an an acidic buffer, the hydrogen ion concentration decreases, and the resulting solution is less acidic than a solution containing the pure weak acid.

  • The Acid Dissociation Constant

    • An understanding of Ka is also essential for working with buffers; the design of these solutions depends on a knowledge of the pKa values of their components.
    • Buffers are used whenever there is a need to fix the pH of a solution at a particular value.
    • Buffering is an essential part of in-vitro biochemical studies and acid-base physiology and plays a key role in analytical chemistry.
    • Compared with an aqueous solution, the pH of a buffer solution is relatively insensitive to the addition of a small amount of strong acid or strong base.