BIOS 251 Week 2 Lab Instructions Chemistry Basics

Student Name

Chamberlain University

BIOS-251 Anatomy & Physiology I

Prof. Name

Date

Week 2 Lab Instructions

Chemistry Basics

This laboratory activity focuses on foundational chemistry concepts, including acids, bases, pH, buffers, and solutions. Students will observe chemical behaviors, measure pH using various methods, evaluate the buffering capacity of strong acids, compare the effectiveness of different antacids, and calculate concentrations of common healthcare solutions. Each student is expected to complete and submit their own lab report, even though activities are performed in groups.

Activity Deliverables and Points Distribution

Activity Section	Description	Points
Part A	Measuring pH using pH Strips	3
Part B	Measuring pH using a pH Meter	6
Part C	Examining the Role of Strong Acids as Buffers	4
Part D	Comparative Analysis of Antacids	8
Part E	Solution Preparation and Analysis	3
Reflection	A 10-14 sentence summary of lab learnings	6
Total		30

Background

Acids and Bases

The pH scale is used to represent the concentration of hydrogen ions (H+) in a solution, thereby indicating whether a substance is acidic, basic, or neutral. A pH less than 7 indicates an acid, while values above 7 represent bases. A pH of exactly 7 is considered neutral, as found in pure water.

Buffers

Buffers stabilize pH by neutralizing added acids or bases. For instance, phosphate buffer is widely used to maintain near-neutral pH levels, particularly in biological applications like contact lens solutions.

Solutions

In chemical solutions, the solute is the lesser component that dissolves in the solvent, which is the greater component. Proper solutions remain uniformly mixed over time without separating.

Lab Purpose

This laboratory aims to enhance students’ understanding of the chemical behaviors of acids and bases, the mechanisms of buffers, the preparation of chemical solutions, and pH measurement techniques.

Required Materials

• Laboratory handout (printed)
• Pen or pencil

Preparation Instructions

• Thoroughly read the entire lab handout before attending.
• Remove any unnecessary items from your workstation.
• Ensure all materials are available and ready.
• Follow both written and verbal instructions from the instructor.

Activity and Observations

Part A: Measuring pH Using pH Strips

In this section, students will use colorimetric pH strips to determine the pH of various solutions, including household substances and unknown chemicals.

Materials: pH strips, DI water, lemon juice, 10% bleach, unknown solutions A and B.

Method: Each pH strip is dipped into a solution and observed for color change, which is then compared to a reference chart.

Solution	Color Description	Estimated pH	Acid or Base
DI Water
Unknown A
Unknown B
Lemon Juice
10% Bleach

Part B: Measuring pH Using a pH Meter

This part focuses on using an electronic pH meter for more precise pH measurement.

Solution	pH (pH Meter)	pH (Strips)	Acid or Base
DI Water
Unknown A
Unknown B
Lemon Juice
10% Bleach

Questions:

1. Based on your results, identify which unknown is HCl and which is NaOH.
2. What consistent trends do you notice among acidic substances?
3. Does the pH of the blood sample suggest it belongs to a healthy individual?

BIOS 251 Week 2 Lab Instructions Chemistry Basics

Part C: Effects of Strong Acids on Buffer Solutions

This experiment compares the pH change in DI water versus a phosphate buffer when exposed to drops of 1 M HCl.

Drops of HCl	pH (DI Water)	pH (Buffer Solution)
0	7.0	7.1
1	6.0	7.1
2	5.5	7.09
3	3.9	7.09
4	3.7	7.09
5	3.1	7.08
6	2.0	7.09
7	1.9	7.1
8	1.8	7.09
9	1.4	7.08

Questions:

1. How does adding HCl affect the buffer solution?
2. Plot the pH vs. number of drops of HCl.
3. Describe the rate of pH change observed in the graph.
4. Compare the changes in pH between DI water and the buffer. What do you notice?

Part D: Antacid Effectiveness Comparison

This section investigates how different antacids neutralize simulated stomach acid.

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

Experiment Procedure:

• Add crushed antacids incrementally to HCl.
• Record the number of tablets needed to reach pH 7.

Brand Name	Tablets Used	Active Ingredient	Amount/Tablet
Tums
Alka-Seltzer

Questions:

1. Are the active ingredients in antacids considered acids or bases?
2. What chemical reaction causes the pH to increase in stomach acid?
3. Calculate the total amount of active ingredient used (Table below):

Brand Name	Total Active Ingredient (mg)
Tums
Alka-Seltzer

1. Based on your results, which antacid is more effective and why?

Part E: Preparing a Normal Saline Solution

Normal saline is widely used in healthcare to maintain hydration. The solution is composed of NaCl dissolved in water and sterilized.

Preparation Example:

• 4.5 g of NaCl dissolved in 500 ml of water, sterilized by heating.

Questions:

1. What is the % mass/volume concentration of this solution?
2. Given a molarity of 0.154 M, what is the osmolality?
3. If evaporation occurs during sterilization, would the solution become more or less concentrated? Explain.

Reflection

This lab enhanced my understanding of core chemistry principles applied in real-life scenarios. I learned how to measure pH using both pH strips and meters, and how to interpret differences in accuracy between them. I observed how buffers maintain a stable pH despite the addition of strong acids, which is crucial in biological systems. The antacid comparison was particularly interesting, demonstrating neutralization reactions and reinforcing the importance of understanding active ingredients. I also appreciated learning how saline solutions are prepared and why precision in concentration is vital in clinical settings. This lab connected theoretical chemistry concepts to practical applications, helping me understand their significance in healthcare and laboratory science.

References

Saladin, K. S. (2020). Anatomy & physiology: The unity of form and function (9th ed.). McGraw-Hill Education.

BIOS 251 Week 2 Lab Instructions Chemistry Basics