Define buffer and pH, and pH scale. State the importance of pH.
Buffer:
Buffer is a solution or mixture of weak acids and their conjugate base or of weak bases and their conjugates acids. Which have the ability to resist a change in pH, following addition of moderate amount of strong acid or bases.
Or ,
A buffer is substance that has the ability to bind or release H+ in solution, thus keeping the pH of solution relatively constant despite the addition of considerable qualities of acid or bases.
pH:
The term pH was introduced in 1909 by sorensen. It is the negative log of the hydrogen ion concentration.
PH= -log(H⁺)
pH value:
- The PH value of a substance is directly related to the ratio of the hydrogen ion and hydroxyl ion.
- If the H⁺ concentration is higher than OH־, the material is acid.
- If the OH־ concentration is higher than H⁺, than the material is basic
- 7 is neutral , < is Acid, > 7 is basic
The pH Scale:
- The PH scale is corresponds to the concentration of hydrogen ion.
- Pure water H⁺ ion concentration is 1×1=7M, therefore the PH would than be 7.
PH value is shown by different color in universal indicator
Measurement of pH:
pH can be measured by:
- Maintenance of ECF between 7.35 and 7.45 is essential for health.
- Enzymatic activity: For optional activity of appropriate pH range must be within an optimal limit.
- For homeostasis: Maintenance of appropriate pH is necessary for homeostasis.
- Maintains the native molecular from and structure conformation of bio-molecules ( especially proteins) at which they are functionally active.
- Disturbances of acid-base balance are diagnosed by measuring the pH of arterial blood.
- Blood pH<7.35 indicates acidosis which occurs in diabetic ketoacidosis etc.
- blood pH >7.45 indicates alkalosis which occurs in the vomiting of acids gastric contents or treatment with certain diuretics.
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