BIOS 251 Week 2 Lab Instructions Chemistry Basics

BIOS 251 Week 2 Lab Instructions Chemistry Basics

Name

Chamberlain University

BIOS-251 Anatomy & Physiology I

Prof. Name

Date

Lab Instructions: Chemistry Basics

Activity Deliverable Points

Step 1: Read the Entire Lab Packet

1.0 Thoroughly review the entire laboratory packet. (Refer to the attached sheets.)

Step 2: Come to the Lab with Proper PPE

BACKGROUND:

Acids and Bases

As discussed in your weekly modules, pH is a measure of proton (H⁺) concentration in a solution. The pH scale, ranging from 0 to 14 for most substances, measures acidity and basicity. Generally, acids have pH values below 7, while bases have values above 7, with a pH of 7 considered neutral, characteristic of pure water.

Buffers

This week, you learned that buffers resist changes in pH. A phosphate buffer was prepared for this lab, commonly used for contact lens storage to maintain a pH close to that of natural tears.

Solutions

In solutions, the solute is the lesser component, and the solvent is the predominant one. It’s important to remember that solutes and solvents do not separate over time.

PURPOSE:

In this lab, you will explore essential chemicals and their properties. You will learn various techniques to measure the pH of different solutions and understand the concepts of neutralization, the behavior of acids in water, and the preparation of solutions at varying concentrations.

MATERIALS:

Each lab group will observe demonstrations from the instructor. Be sure to print a copy of this lab document for each group member along with necessary writing utensils.

PREPARATION:

• Read the entire lab packet before attending class.
• Clear your workspace of unnecessary items. Store bags and other materials safely.
• Gather all required materials listed above.
• Familiarize yourself with the lab materials.
• Adhere to the instructions in the packet and those provided by your instructor.
• Record your own data and prepare your own lab report, even when working in a group.

ACTIVITY:

Review the observation report, complete the tables, and answer the questions fully to earn full credit. Utilize available resources such as textbooks and lecture notes for accurate responses.

OBSERVATION REPORT: W2 Lab Worksheet: Chemistry Basics

Measuring pH

Different areas of the body maintain specific optimal pH levels. For instance, blood typically has a pH range between 7.35 and 7.45. This experiment examines various common household chemicals to investigate their pH levels.

Part A: Measuring pH with pH Strips

Materials: DI water, lemon juice, 10% bleach, unknown solutions

Method:

1. Obtain pH strips.
2. Dip each pH strip into the solution, using a new strip for each sample.
3. Estimate pH and determine if each solution is acidic or basic by comparing against the provided pH guide.

Table 1:

Part B: Measuring pH with a pH Meter

Using a pH meter provides an accurate measure of H⁺ ion concentration. Dip the pH meter into each solution and record the pH values.

Table 2:

Questions:

1. Based on your pH measurements, determine which unknown solution corresponds to HCl or NaOH.
2. Note any trends observed regarding the acidic solutions.
3. Does the pH of the blood sample suggest it is from a healthy individual?

Part C: Impact of Strong Acids on Buffers

Description of Experiment:

This experiment assesses how strong acids affect pH in both water and a phosphate buffer solution by adding HCl dropwise.

Table 3: Data Collected from Experiment

Questions:

1. What effect does adding 1 M HCl have on the pH of the buffer solution?
2. Create a graph of pH versus drops of 1 M HCl.
3. Describe the rate of pH change observed in the graph.
4. Compare the changes in pH when adding 1 M HCl to both DI water and the buffer solution, noting similarities and differences.

Part D: Comparing Antacids

Have you ever taken an antacid for heartburn relief? Stomach acid is approximately 0.36 M HCl. In this section, we will compare various antacids against simulated stomach acid to determine their effectiveness.

Materials: 0.36 M HCl, beakers, pH strips, Tums, Alka-Seltzer

Experiment:

1. Pour 20 mL of stomach acid (0.36 M HCl) into two beakers (A and B).
2. Measure and record the initial pH of the acid in both beakers.
3. Crush and add Tums to beaker A, measuring pH after each tablet until reaching 7.
4. Repeat steps 2-3 for Alka-Seltzer in beaker B.
5. Record results in the following table.

Table 4:

Questions:

1. Are the active ingredients of the antacids classified as acids or bases?
2. How does the active ingredient change the pH of the stomach acid?
3. Calculate the total active ingredient required based on your results.

Part E: Solutions

This section reviews the preparation of solutions, focusing on a normal saline solution commonly used in healthcare.

Preparation of Normal Saline:

To prepare a 500 mL bag of normal saline, dissolve 4.5 g of NaCl in water, heating the solution for sterilization before transferring it to a sterile bag.

1. What percentage concentration (% mass/volume) should be labeled on the bag?
2. Given a molarity of 0.154 M NaCl, what osmolality would you expect for this solution?
3. If evaporation during sterilization alters the volume, how would that affect the solution’s concentration?

Reflection:

Reflect on four key concepts learned during this lab. Be specific and ensure your response is comprehensive, totaling 10-12 sentences.

LAB REPORT IS DUE PRIOR TO THE DATE ASSIGNED BY YOUR PROFESSOR.

Grading Rubric:

BIOS 251 Week 2 Lab Instructions Chemistry Basics

References:

• Saladin, K. S. (Year). Anatomy & Physiology: The Unity of Form and Function. Publisher.