BIOS251 W2 Lab Instructions (done)

Week 2 Lab Instructions Chemistry Basics Activity Deliverable Points Part A Measuring pH using pH Strip 3 Part B Measuring pH using pH Meter 6 Part C Strong Acids as Buffers 4 Part D Comparing Antacids 8 Part E Solutions 3 Reflection 10-14 Sentence Reflection 6 References: 1. Saladin   Anatomy & Physiology: The Unity of Form and Function Step 1: Read the Entire Lab Packet 1.0 – Read through the laboratory packet – SEE ATTACHED SHEETS Step 2: Come to the Lab with Proper PPE BACKGROUND: Acids and Bases As you studied in your weekly modules, the pH is the measure of proton (H + ) concentration in a solution. The pH scale is used to measure the acidity or basicity of a solution. With few exceptions for exceptionally strong acids and bases, pH values fall between 0 and 14. Acids have low pH values that range from 0 to less than 7 while bases have higher pH values that range from greater than 7 to 14. A pH of 7 is neutral and is the pH of pure water. Buffers As you learned in your modules this week, buffers resist pH change. To further explore this property, phosphate buffer was prepared. Phosphate buffers are the type of buffer used for storing contacts, ensuring a pH of near the natural pH of the eye. Solutions As a review, the term solute refers to the minor portion of the solution and the term solvent is the major, more abundant portion of the solution. Keep in mind that in solutions, the solute and solvent do not separate when allowed to stand. BIOS251 Week 2 Lab Instructions Page 1 of 10

PURPOSE: In this lab, you will be asked to explore important chemicals and chemical properties. You will learn how to measure pH of solutions with different techniques and how they compare. You will also learn about the concept of neutralization, the behavior of acids in water and buffers, and how to prepare solutions of different concentrations. MATERIALS: Each lab group will observe demonstrations prepared by your instructor. You will also need to print off a copy of this lab document.  A copy of the lab report for each member of your group  A writing utensil PREPARATION:  Read your lab in its entirety before coming to class.  Clear your workstation of all unnecessary materials. Book bags and or purses should be hung on hooks or places at the front of class. Make sure all other unnecessary materials (coats, drink containers, unused textbooks, etc.) are all stored and placed in a safe area out of the way.  Obtain all materials listed above.  Familiarize yourself with your lab materials.  Follow the directions of the packet and as presented by your instructor.  Be aware of the instructions for documenting your lab work. You will be performing the lab in a group but will each be responsible for recording your own data and creating your own lab report. ACTIVITY: o Read through each table and question on the observation report and fill in the appropriate answers. Make sure you are answering each question completely for full credit. You may use any of the provided resources (textbook, lecture materials, etc.) to accurately answer. BIOS251 Week 2 Lab Instructions Page 2 of 10

Table 2: Solution pH value using a pH meter pH values using strips from part A Conclusion: Acid or base DI water 8.1 6 Acid Unknown A 2.0 1 Acid Unknown B 12.2 11 Base Lemon Juice 2.5 3 Acid 10% Bleach 6.8 9 Base Questions: 1. Unknown solutions A and B are 0.1 M solutions of either HCl or NaOH. According to your pH measurements, which is which? Solution A is HCI and Solution B is NaOH. 2. What trends do you notice about the acidic chemicals? The lower the number the more acidic they are. 3. Based on the pH of the blood sample, do you feel that this sample came from a healthy individual? Blood pH range is between 7.35-7.45. Part C: How does a strong acid effect the pH of a buffer? Description of experiment: In an experiment to measure the effect of a buffers, strong acid was added dropwise to two different beakers, one of water and one of phosphate buffer solution. Below are the results of this experiment. BIOS251 Week 2 Lab Instructions Page 4 of 10

Table 3: Data collected from experiment Measurement number Drops of HCl Water pH Buffer Solution pH 1 0 (initial pH of DI water) 7.0 7.1 2 1 st drop 6.0 7.1 3 2 nd drop 5.5 7.09 4 3 rd drop 3.9 7.09 5 4 th drop 3.7 7.09 6 5 th drop 3.1 7.08 7 6 th drop 2.0 7.09 8 7 th drop 1.9 7.1 9 8 th drop 1.8 7.09 10 9 th drop 1.4 7.08 Questions: 1. How does the addition of 1 M HCl change the pH of the buffer solution? According to the data collected, it did not change much the pH of the solution. 2. Graph the pH as a function of the drops of 1 M HCl added. The pH should be on the Y-axis and the drops of 1 M HCl on the X-axis. 0.5 1 1.5 2 2.5 3 0 0.5 1 1.5 2 2.5 3 3.5 Y-Values BIOS251 Week 2 Lab Instructions Page 5 of 10

Part D: Comparing Antacids Have you ever taken an antacid for relief heartburn? Stomach acid is approximately 0.36 M HCl. Antacids such as Tums are often taken to treat heart burn. Reaction between an antacid and stomach acid is a neutralization reaction. In this exploration, we will use simulated stomach acid to pit several antacids against each other to see which is the most potent. Materials: 0.36 M HCl, beakers, pH strips, tums, Alka-Seltzer Experiment: 1. Place 20 ml of stomach acid (0.36M HCl) in two beakers (A and B) 2. The chemist measures the pH of the acid in beakers. pH value of acid is ________________. 3. Crush tablet of Tums, one at a time and add it to beaker A. 4. Measure pH of solution using pH strip. 5. Keep adding tablets, one at a time until pH of solution is 7. 6. Repeat the steps 2-6 using Alka-Seltzer, one at a time to beaker B, one at a time, until the pH of the solution is 7. 7. The chemist records the values into the table below Table 4: Brand name of Antacid Total number of tablets required to neutralize simulated stomach acid Active ingredient (research online) Active ingredient amount per tablet Tums 5 Calcium 1000 mg Alka-Seltzer 6 Anhydrous Citric Acid, Sodium Bicarbonate, Asprin 1000 mg 1916 mg 325 mg Questions: 1. In terms of acid base chemistry, are the active ingredient of antacids considered acids or bases? The active ingredient of antacids are considered bases. 2. Using the acid/base terminology we learned this week, what causes the pH change of the stomach acid? The stomach acid pH is very low on the pH scale (very acidic) as it contains hydrochloric acid necessary to digest food. The changes depend on how much bicarbonate (base) buffer is introduced. BIOS251 Week 2 Lab Instructions Page 7 of 10

3. Calculate the total amount of active ingredient required by multiplying the amount of active ingredient per tablet by the number of tablets used. Show your work in the space given below. Add more space for students Table 4: 4. Based on the data here, which antacid would you choose and why? I would choose tums, although it does not last long I could repeat it throughout the day. I would not take Alka seltzer because I personally do not like the tastes, so I would avoid that as much as possible. BIOS251 Week 2 Lab Instructions Page 8 of 10 Brand name of Antacid Amount of active ingredient required to neutralize simulated stomach acid Tums 5000 mg of Calcium Carbonate Alka-Seltzer 11,496 mg Sodium Bicarbonate 1950 mg Asprin

**LAB REPORT IS DUE PRIOR TO THE DUE DATE AS ASSIGNED BY YOUR PROFESSOR Grading Rubric: Activity Deliverable Points Part A: Complete table 1: 3 points 3 Part B: Complete table 3: 3 points. Complete all questions: 3 points 6 Part C: Complete all questions: 4 points 4 Part D: Complete all questions: 4 points. Complete both tables, 2 points each (4 points total) 8 Part E: Complete all 3 questions: 3 points 3 Reflection Write a 10-14 sentence laboratory reflection: Length: 1 point Completeness: 5 points 6 All Lab Deliverables Total of all activities, reflections, and questions 30 BIOS251 Week 2 Lab Instructions Page 10 of 10