Buffers Keep the Balance

Buffers Keep the Balance - Elena Maxim 4 Hr. Ap Chem...

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Reaction Wells Elena Maxim 4 th Hr. Ap Chem 3/10/2008 Buffers Keep the Balance: Properties of Biological Buffers I. Purpose: The purpose of this lab is to learn more about the properties of buffers and the way they function, thorough observing their effect when both acids and bases are added to the buffers. Buffers are also important components in our body, which keep the pH regulated. Finding out what buffers are made of and how they maintain the delicate pH balance is another factor in this lab. By studying the neutralization and dissociation in weak acids, as well as their conjugate bases, we will observe the effect on the buffer when we add an acid and base, and by observing the pH level, we mirror that of a biological carbonic acid-bicarbonate buffer. In addition, study the comparison between two different phosphate buffers that reflect the physiological role of buffers within cells and determine which is closer to the ideal buffer. II. Procedure: Part A: Model Carbonate Blood Buffer 1. Six medium sized test tubes are set up on a rack and labeled. By using Table 1, a graduated cylinder was used to measure the required amounts of solution and added to each test tube and mixed. Table 1 Test Tube Number 1 2 3 4 5 6 Solution Carbonic Acid (Reference) Model Carbonate Blood Buffer Water Control Model Carbonate Blood Buffer Water Control Sodium Bicarbonate (Reference) Seltzer Water(mL) 4 2 0 2 0 0 Sodium Bicarbonate 0.1 M (mL) 0 2 0 2 0 4 Distilled Water(mL) 0 0 4 0 4 0 2. 5 drops of brothymol blue indicator is added to each test tube and mixed, and the initial color of each test tube is recorded and the initial pH of each solution is measured by using a narrow range pH paper, and recorded. 3. 0.1 M hydrochloric acid is added to the biological buffer solution in test tube 2, being careful to mix the solutions. The number of drops of HCl required to change the color to the same shade of yellow as the reference is counted and it is recorded.
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Elena Maxim 4 th Hr. Ap Chem 3/10/2008 4. HCl is added the same way to test tube 3, and the number of drops are once again counted to reach the desired color change mirroring that of the carbonic acid reference from test tube 1. 5. Using a Beral-type pipette, 0.1 M sodium hydroxide solution is added to the biological buffer in test tube 4, and its contents are mixed, once again the number of drops is counted to mirror the same shade of blue as in the sodium bicarbonate reference solution in test tube 6, and recorded. 6. Another 0.1 M sodium hydroxide solution is added dropwise to test tube 5, to mirror the blue color of test tube 6, and the number of drops is again recorded in table 1. Part B: Biological Phosphate Buffers 1. Two large test tubes are obtained and labeled A and B. 12 mL of NaH 2 PO 4 solution and 3 mL of Na 2 HPO 4 solution are added to test tube A. 8 mL Na 2 H 2 PO 4 solution and 8 mL Na 2 HPO 4 solution are added to test tube B. 2.
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Buffers Keep the Balance - Elena Maxim 4 Hr. Ap Chem...

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