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What Are Buffer Solutions?
Ranging from pH 1 to pH 12, at ReAgent we offer multiple buffer solutions to suit your needs. Prepared in our facilities to high standards, our buffer solutions contain a weak acid or weak base and the respective conjugated base or acid. The main objective of these solutions is to prevent a great pH variation when strong acids or bases are added. This buffering ability is achieved via the equilibrium between the acid (HA) and its conjugated base (A-), according to the reaction:
HA H+ + A-
Le Chartelier’s principle
According to this principle, if a strong acid is added to a buffered solution, or in other words containing a weak acid and its conjugated base, pH is not significantly altered and the above reaction only moves slightly to the left. As a result, the H+ concentration (which determines how acidic a solution is) increases less than what would be expected due to the amount of acid added. Following a similar process, adding a strong base consumes much less H+ than anticipated. In the absence of the buffer, adding a strong acid or base would seriously alter the solution’s pH.
Inside the comfort zone
For every buffer solution, there’s a comfort zone when the concentration of acid (HA) is in equilibrium with the concentration of its conjugated base (A-), or in other words [HA]=[A-]. Within this zone, it shows the best buffering capacity. For example, if a strong base is added, the H+ concentration is only marginally reduced as most of the OH- is consumed in the following reaction:
OH- + HA → H2O + A-
Only a small proportion is used in the reaction that actually alters the pH (neutralisation reaction):
OH- + H+ → H2O
Outside the comfort zone
Buffering solutions are only valid within a certain pH range, and once either the upper or lower limit is crossed (the acid present reaches over 95% deprotonation), the solution is no longer protected and adding a strong acid or base will result in considerable pH changes. This is usually associated with colour changes in the solution for easy identification.
Solutions vs. powder sachets
Although ready-made solutions are still the most popular option, many laboratories now prefer to use powder sachets. These products offer significant advantages, including smaller, lighter and easier to transport and store; as well as a longer shelf-life.
