10 Facts on Buffers

By Philip McIntosh
Published: March 13, 2017 | Last updated: April 21, 2021 12:02:53
Presented by Cyco Flower

Key Takeaways

In the horticulture world, a buffer works wonders.

The term buffer is used in a lot of ways. In general usage, it suggests a cushion or barrier of some kind between two zones. Chemically, the meaning is analogous.
In chemistry, a buffer is a solution that resists a change in pH. So, it sort of “cushions” a solution against large or rapid variations in acidity or basicity.
A well buffered solution can take a reasonable addition of strong acid or base, and react in such a way as to take H⁺ or OH^-ions out of solution, thus keeping the acid-base balance relatively stable.
Buffers themselves can either be acidic (pH < 7) or basic (pH > 7).
Buffers are made by combining a weak acid in solution with its conjugate (weak) base.
A generic acid, HA has a conjugate base of A^-, where H is a proton to be released as H⁺ (that makes it an acid) and A^- is a counter ion (which could be a lot of things).
An example: Phosphoric acid (H₃PO₄) is a weak acid where there are three possible H⁺ ions to be released (the H part) and the PO₄^-3 (that’s the A^- part). If we combine it in solution with sodium phosphate (Na₃PO₄) we provide some sodium ions and more of the phosphate PO₄^-3 (that’s the conjugate base).
In the above example, only a little of the H₃PO₄ionizes (because it is a weak acid) and much of the H₃PO₄remains un-ionized in solution.
If a strong acid is added to this solution, it will preferentially react with the free PO₄^-3 (mostly from the Na₃PO₄) rather than water to make more of the weak acid H₃PO₄ instead of H₃O⁺ so the pH doesn’t change much at all.
If a bit of strong base (OH^-) is added to the solution, the weak acid (H₃PO₄) will release one of it’s protons to combine with the OH^- to create water (H₂O) and again the pH doesn’t change much at all.

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Written by Philip McIntosh | Science & Technology Writer, Teacher

Philip McIntosh is a science and technology writer with a bachelor’s degree in botany and chemistry and a master’s degree in biological science. During his graduate research, he used hydroponic techniques to grow axenic plants. He lives in Colorado Springs, Colorado, where he teaches mathematics.

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