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Activity No. 1

  1. Note: The buffer equations states that the
    pH of a solution containing a weak acid its salt is determined by the value of the pKa of the acid and by the ratio of the salt/acid concentrations in solutions.
  2. ______ are of primary importance in regulating the pH of the fluids and tissues of lving organisms within the limits consistent with life and normal function.
    Buffer
  3. In the preparation of a buffer solution from a weak acid and its salt the following steps are considered:
    • 1. Choose the weak acid whose pKa is closest to the desired pH. This insures maximum buffer capacity.
    • 2. Consider the individual concentration of the buffer salt and acid needed to obtain a suitable buffer capacity. Concentration ranges 0.05 M to 0.50 M. Buffer capacity ranges 0.01 M to 0.10 M.
    • 3. From the Henderson-Hasselbach equation calculate the ratio of salt and weak acid required to obtain the desired pH. This buffer equation is satisfactory within a pH range of 4 to 10.
    • 4. Mix calculated amounts (volume) of acid and salt.
    • 5. Check the pH using a pH meter.
  4. ________ is one that resists drastic changes in H+ concentration when small amounts of acid or base are added.
    Buffer Solution
  5. Example of a buffer solution:
    an aqueous solution of acetic acid with sodium acetate; and an aqueous solution of ammonia with ammonium chloride
  6. All biological processes are affected by the ______ or ______ of the medium in which they occur.
    Acidity, Alkalinity
  7. ______ is the active participant in many biochemical reactions.
    Water
  8. Water makes up about _______ of the human body and other animals.
    70%
  9. The H+ concentration is conveniently expressed in terms of _____
    pH
  10. The use of buffers is an important part of many industrial processes like:
    fermentation, electroplating, manufacture of leather, photographic materials, and dyes.
  11. The body is however, equipped with remarkably efficient control processes which prevent the sudden variation of H+ concentration as a result either the introduction of acidic and basic substances from outside or as products of some metabolic processes. These mechanisms are:
    • (1) the buffer systems of the body
    • (2) the action of the kidneys in which acids and bases are excreted in the urine
    • (3) respiratory mechanisms in which H+ ion concentration in the body fluids is regulated by the rate of CO2 elimination in the lungs.
  12. The ____ concentration of an aqueous solution may affect the conformation and structures of substances and the concentration of molecular and charged species.
    H+
  13. The pH of a buffer solution made up of a weak acid and its salt can be calculated with the use of the ____________
    Henderson-Hasselbach equation (Buffer equation)
  14. In living cells most biochemical reactions take place in an _____________
    Aqueous Environment
  15. A buffer is made up of:
    weak acids and their salts or weak bases and their salts
  16. LAB ACTIVITY:
    Materials:
    Chemicals:
    Procedure:
    Image Upload 2
  17. The pKa of some commonly used buffer acids:
    Image Upload 4
  18. For a buffer solution made of weak base and its salt the buffer equations is:
    • Image Upload 6
    • where pKw is equal to 14 at 25°C, this is negative logarithm of  the ionization constant of water and pKb is the negative logarithm of the ionization constant of the base.
  19. Write or give the buffer equation
    • Image Upload 8
    • where pKa is the negative logarithm of the ionization constant of the weak acid.
  20. The buffer systems of the body are made up of a weak acid and their salts as well as proteins. Give the examples of human body fluids and their buffer systems.
    Image Upload 10
  21. What is the title of Activity No. 1?
    PREPARATION OF BUFFERS
Author
JhanAxis
ID
359892
Card Set
Activity No. 1
Description
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