buffer_lab[1] - R ichard Yoon Buffers Keep the Balance I....

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Richard Yoon Buffers Keep the Balance I. Purpose: Observe and learn about buffers, their necessity in human body, how they work, and what their importance is in maintaining a proper pH level. We will be studying the relationship between buffers and pH levels, process of dissociation and neutralization, weak acids, and conjugate bases (observing the effected of added acid and base oh pH level and buffer capacity, modeling 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 was closer to the ideal buffer. II. Procedures: Part A: Model Carbonate Blood Buffer 1. Set up six medium-size test tubes in a rack. Label them 1-6. 2. With Table 1 as a guide, use a graduated cylinder to measure and add the indicated volumes of the required solutions to each test tube. 3. Mix the contents of each test tube thoroughly by gentle shaking or swirling. 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
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4. Add 5 drops of bormthymol blue indicator solution to each test tube 1 to 6. Shake to mix. Record the initial color for each solution 1-6 in Data Table 1. 5. Measure the initial pH of each solution using a piece of narrow-range pH paper, pH 6.0-8.0. Record the results in Data Table 1. 6. Use a Beral-type pipet to add 0.1 M hydrochloric acid solution dropwise to the biological buffer solution in test tube 2. Be sure to swirl the contents periodically to ensure thorough mixing. 7. Count the number of drops of HCl required to change the color to the same shade of yellow as the carbonic acid reference solution in test tube 1. Record the number of drops in Data Table 1. 8. Use a Beral-type pipet to add 0.1 M hydrochloric acid solution dropwise to the water control solution in test tube 3. Count the number of drops of HCl required to change the color to the same shade of yellow as the carbonic acid reference solution in test tube 1. Record the number of drops in Data Table 1. 9. Use a Beral-type pipet to add 0. M sodium hydroxide solution dropwise to the biological buffer solution in test tube 4. Be sure to swirl the contents periodically to ensure thorough mixing. 10. Count the number of drops of Na OH required to change the color to the same shade of blue as the sodium bicarbonate reference solution in test tube 6. Record the number of drops in Data Table 1. 11. Use a Beral-type pipet to add 0.1 M sodium hydroxide solution dropwise to the water control solution in test tube 5. Count the number of drops of NaOH required to change the color to the same shade of blue as the sodium bicarbonate reference solution in test tube 6. Record the number of drops in Data Table 1.
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buffer_lab[1] - R ichard Yoon Buffers Keep the Balance I....

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