Anatomy and physiology labs ||

Experiment 1Breathing and the Acid-Base Balance Experiment Inventory

Materials 5 mL Saturated (15%) Sodium Bicarbonate

Solution, NaHCO3

5 mL Sodium Bicarbonate Buffer Solution,

NaHCO3

1 mL Phenol Red, C19H14O5S

Straw

*Permanent Marker

*Distilled Water

Labware (2) 250 mL Beakers

100 mL Graduated Cylinder

10 mL Graduated Cylinder

(1) Pipette

*Stopwatch/Timer

Note: You must provide the materials listed in *red.

EXPERIMENT 1: BREATHING AND THE ACID-BASE BALANCE This experiment will demonstrate the role of the bicarbonate buffer system in regulating carbon dioxide-based acidity in the body.

PROCEDURE 1. Use the permanent marker to label two 250 mL beakers as 1 and 2.

2. Use the 100 mL graduated cylinder to measure and pour 50 mL of distilled water into Beaker 1.

3. Use the 100 mL graduated cylinder to measure and pour 48 mL of distilled water into Beaker 2.

4. Use the 10 mL graduated cylinder to measure and pour 1 mL of saturated sodium bicarbonate solution into Beaker 1. Then, add 2 drops of phenol red to Beaker 1. Gently mix the solution.

5. Use the straw to blow bubbles into Beaker 1. Start the stopwatch as soon as you start blowing into the straw.

Note: DO NOT breathe in when your mouth is on the straw. Inhalations should be taken only with your mouth removed from the straw.

6. Observe the color of the solution as you blow into the straw, and record how long it takes for the pH indicator (phenol red) to change from pink/red (basic) to yellow (acidic).

Note: Take care not to become lightheaded as you blow into the straw. If you become light headed, stop breathing into the straw. Continue only when you no longer feel lightheaded. Blow into the straw for no more than 5 minutes. If you do not see a change within 5 minutes, record “no change” as your observation.

7. Record your observations in Table 1.

8. Use the 10 mL graduated cylinder to measure and pour 1 mL of saturated sodium bicarbonate solution into Beaker 2.

9. Use a pipette to add five drops of the sodium bicarbonate buffer solution to Beaker 2. Then, add 2 drops of phenol red to Beaker 2. Gently swirl the solutions to create a homogeneous mixture.

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10. Use the straw to blow bubbles into Beaker 2. Start the stopwatch as soon as you start blowing into the straw.

Note: DO NOT breathe in when your mouth is on the straw. Inhalations should be taken only with your mouth removed from the straw.

11. Observe the color of the solution as you blow into the straw, and record how long it takes for the pH indicator (phenol red) to change from pink/red (basic) to yellow (acidic).

Note: Take care not to become lightheaded as you blow into the straw. If you become light headed, stop breathing into the straw. Continue only when you no longer feel lightheaded. Blow into the straw for no more than 5 minutes. If you do not see a change within 5 minutes, record “no change” as your observation.

12. Record your observations in Table 1.

© eScience Labs, 2016

Data Sheet Experiment 1 Data Sheet Table 1: Color Change of Sodium Bicarbonate Solution With and Without Buffer

Beaker Starting Color Final Color Time to Change to Final Color Beaker 1 Beaker 2

© eScience Labs, 2016