What Is Osmosis?

The Biotechnology Education Company®

S-74 EDVO-Kit #

What Is Osmosis?

Storage: Store this experiment a room temperature.

EXPERIMENT OBJECTIVES:

• Students will predict the net movement of molecules across a semipermeable membrane. • Students will define what molecules move during diffusion and osmosis. • Students will understand that osmosis and diffusion are important principles in animal and plant physiological systems.

All components are intended for educational research only. They are not to be used for diagnostic or drug purposes, nor administered to or consumed by humans or animals.

The Biotechnology Education Company ® • 1-800-EDVOTEK • www.edvotek.com

EVT 007157AM 2 EDVO-Kit # S-74 What is Osmosis?

Table of Contents

Page

Experiment Components 3 Experiment Requirements 3

Background Information 4

Experiment Procedures Experiment Overview 6 Activity One - Learning About Osmosis and Dialysis Membrane 7 Activity Two - Effect of Salt on Osmosis 8 Activity Three - Dialysis of Juice Pigments 9 Critical Thinking and Hypothesis Development 10 Study Questions 10

Instructor's Guidelines Notes to the Instructor 11 Suggestions for Lesson Plan Content 12 Connections to National Content Standards 13 Connections to National Skill Standards 14 Pre-Lab Preparations 14 Study Questions and Answers 15

Material Safety Data Sheets 16

The Biotechnology Education Company ® • 1-800-EDVOTEK • www.edvotek.com 3 EDVO-Kit # S-74 What is Osmosis?

Experiment Components

This experiment is designed for 5 groups. Storage: Store entire experiment Contents at room temperature.

• Orange Dye, Low Molecular Weight Dye • Blue/Green Dye, High Molecular Weight Dye • 1 Roll of Dialysis Tubing (7 feet) • 5 Transfer pipets

Requirements

• Table Salt • Beakers or Jars (600 ml, approximately the size of the packaging tube) • Distilled or Deionized Water • Spoon • Apple Juice, Beet Juice, or Equivalent Juices

All components are intended for educational research only. They are not to be used for diagnostic or drug purposes, nor administered to or consumed by humans or animals.

EDVOTEK - The Biotechnology Education Company ® 1-800-EDVOTEK • www.edvotek.com 24-hour FAX: (301) 340-0582 • email: [email protected] 4 EDVO-Kit # S-74 What is Osmosis? Sci-On® Biology

An Introduction to Osmosis

Molecules undergo constant motion, which enables them to move from one region to another. The motion of a molecule in solution is constantly affected by collisions with other molecules, which results in random motion. Diffusion, which is important to living systems, occurs in response to molecular motion and to a concentration gradient, that is, molecules moving from areas of high concentration to areas of low concentration until an equilibrium is reached. Examples include the oxygenation of blood in the lungs and the exchange of nutrients into cells and waste products out of cells.

During osmosis, the diffusion of water molecules down a concentration gradient occurs across a semi-permeable membrane. A semi– permeable membrane is a membrane which allows some materials to pass through while rejecting others. This is true of the plasma membrane surrounding all living cells. Dialysis tubing can be used to demonstrate the properties of a semi-permeable membrane in relation to osmosis. For example, if one fills a piece of dialysis tubing with a 5% salt solution (95% water) and places the tubing into a 100% water bath, water molecules will move from the water bath, a region with a higher concentration of water

Background Information Background molecules, into the tubing which has a lower concentraion of water molecules. The tubing, being semi- permeable, allows only the smaller water molecules to move through the pores. The membrane is imperme- able to salt and therefore salt cannot move through the pores. The net result is a swelling in the bag size due to the influx of water molecules.

An Introduction to Osmosis

If the liquid in the dialysis tubing is 100% water and the bath outside the tubing is a 5% salt solution, then there will be a flux of water out of the tubing, which will result in shrinkage of the tubing. In the case where the concentration of water is equal on both sides of the dialysis

Background Information membrane, that is, the liquid in the bath is the same concentration as that in the dialysis tubing, then no change in tubing will result. An equilibrium exists between the water molecules inside and outside the tubing. (Figure 3)

Dialysis membranes are made of purified cellulose containing micro- scopic pores. The pore size is controlled during manufacturing. The pore size determines the membrane’s permeability to molecules of different sizes. This assumes that these molecules have similar shapes. The dialysis tubing being used in this experiment will allow only low molecule weight molecules to pass through the membrane, while larger molecules will remain in the dialysis tubing.

Experiment Overview

EXPERIMENT CONTENT OBJECTIVE

WORKING HYPOTHESIS

If the movement of molecules is from a higher concentration to a lower concentration through a semi-permeable membrane, then qualitative results to demonstrate this principle can be observed in experimental procedures.

Experiment Procedures BEFORE YOU START THE EXPERIMENT

1. Read all instructions before starting the experiment.

2. Write a hypothesis that reflects the experiment and predict experimental outcomes.

LABORATORY SAFETY Wear gloves and safety 1. Gloves and goggles should be worn routinely as good goggles laboratory practice.

2. DO NOT MOUTH PIPET REAGENTS - USE PIPET PUMPS.

3. Always wash hands thoroughly with soap and water after handling reagents or biological materials in the laboratory.

Activity One - Learning about Osmosis and Dialysis Membrane

WORKING HYPOTHESIS

If a semi-permeable membrane allows for molecules of a certain size to pass through, then one can determine relative sizes of colored

molecules based on color changes in the surrounding solution. Experiment Procedures

EXPERIMENT PROCEDURE

1. Prepare two pieces of dialysis tubing as follows: Carefully tie an overhand knot at one end of moist dialysis tubing. Tie the knot approximately one inch from the end.

2. Prepare the dialysis bath by completely filling a clean beaker or jar with water.

3. Fill the first dialysis bag with blue/green dye: • Roll the untied end of the dialysis bag between your thumb and pointer finger to open the end of the bag. • Squeeze the transfer pipet bulb and fill it with dye up to a level just below the pipet bulb. • Gently insert tip of the transfer pipet deep into the bag. • Apply pressure on the bulb to transfer the contents of the pipet to the dialysis bag. • Carefully tie a knot at the open end of the bag and place it in the beaker of water.

4. Rinse the transfer pipet in water and fill the second dialysis bag with orange dye. Follow the same procedures as in step 3. You should now have two filled dialysis bags (one blue/green, and one orange) in a beaker of water.

5. After 15 minutes, observe if there is any color change in the dialysis bath water.

6. One at a time, remove each bag filled with dye and observe its contents. Is there any change in the color? Put the dialysis bags back in the beaker.

7. Periodically check the color of the bags and dialysis bath water and determine if any color change has occurred in either the bags or the bath water. Save the dialysis tubes that still contain dye in a 8. Which of the two dyes has a smaller molecular size? Why? Which container of water until has a larger molecular size. you are ready to perform Activity Two. 9. Record your results.

Activity Two - Effect of Salt on Osmosis

WORKING HYPOTHESIS

If water molecules move from a higher concentration of water molecules to a lower concentration, then a dialysis bag containing a colored dye and placed into a salt solution, will shrink in size if the concentration of water molecules is higher in the bag than in the surrounding solution.

EXPERIMENT PROCEDURE

1. Prepare a fresh dialysis bath as described in Activity One.

2. Add 3 Tablespoons of salt to the dialysis bath. Stir until the salt is dissolved.

3. From Activity One, obtain the dialysis bag that still contains dye.

Hint: This is the high molecular weight dye, and it did not pass Experiment Procedures through the dialysis membrane.

4. Place the dialysis bag saved from Activity One into the dialysis bath that now contains salt.

5. After 15 minutes, observe if there is any change in the dialysis bag. Has the color changed? Does the volume of the bag appear the same or different?

6. Periodically check to see if any changes in color or volume has occurred.

7. Initially, there will be a flux of water out of the dialysis bag into the bath, which has a high salt concentration. This will result in shrinkage of the volume inside the bag. What happens to the dye when the volume shrinks?

8. Record your Results

Activity Three - Dialysis of Juice Pigments

WORKING HYPOTHESIS

If a semi-permeable membrane allows for molecules of a certain size to pass through, then one can determine relative sizes of juice

Experiment Procedures pigments based on color changes in the surrounding solution.

EXPERIMENT PROCEDURE

1. Obtain a clear, non-particulate fruit or vegetable juice that contains a pigment, such as beet, cranberry, or apple juice. Each group can use the same juice, or can choose different juices.

2. Prepare a fresh dialysis bag and a fresh dialysis bath as in Activity One.

3. Prepare the dialysis bag with the juice your group has chosen and place it in the dialysis bath.

4. After 15 minutes, observe if there is any color change in the dialysis bath water or dialysis bag.

5. Periodically check the color of the bags and dialysis bath water and determine if any color change has occurred in either the bags or the bath water.

6. From the dialysis, it is possible to visually determine the relative size of some dye molecules. In this activity, the semi-permeable membrane will permit the passage of molecules which are small, but will not allow the passage of large ones.

7. What can you tell about the size of the juice pigment chosen by your group? Compare your group's result with the results from the other four groups in your class.

8. Record your Results

Critical Thinking and Hypothesis Development

Record the following in your Laboratory Notebook or as instructed by LAB NOTEBOOK your teacher. For each activity (Activities 1, 2 and 3), answer the following:

1. What is the variable?

2. What is the control?

3. What could be changed if the activity was repeated?

4. Write a hypothesis that would reflect a change.

Study Questions

Experiment Procedures

Record the answers to the following Study Questions in your Labora- LAB NOTEBOOK tory Notebook or as instructed by your teacher.

1. Differentiate between diffusion and osmosis.

2. What evidence from this experiment supports the idea that molecules are constantly in motion?

3. What is meant by a semi-permeable membrane?

4. What determines a membrane’s permeability to molecules of different sizes? Give a concrete example from Activity #1.

5. In Activity #2, what happened to the overall size of a dialysis bag when placed into a salt dialysis bath? Explain.

6. Give examples from Activity #3 of different juice pigments that pass through and those that do not pass through a semi-permeable membrane.

Notes to the Instructor

Class size, length of laboratory sessions, and availability of equipment are factors which must be considered in the planning and the imple- mentation of this experiment with your students. These guidelines include Suggestions for Lesson Plan Content which can be adapted to fit your specific set of circumstances.

Instructor’s Guide EXPERIMENT HINTS AND HELP

EDVOTEK experiments are easy to perform and are designed for maximum success in the classroom setting. However, even the most experienced students and teachers occasionally encounter experimental problems or difficulties.

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Suggestions for Lesson Plan Content

This lesson plan outline, written by a teacher, can be used as a guideline for classroom discussion. Connections to the National Content and Skills Standards follow.

Purpose To introduce students to the principle behind the movement of molecules across cell membranes.

Focusing Event Students should understand the concept behind the net movements of molecules. They should be able to distinguish between diffusion and osmosis. They should understand what semi-permeable means in relation to the movement of molecules.

Prerequisite Knowledge Information covered in the background and introduction section

Instructor’s Guide Instructor’s found on page should be thoroughly discussed both before setting up the experiment and after the experiment has been run.

Experimental Skills Students will set up three experimental chambers with each one holding a dialysis bag filled with an experimental solution. They will compare and observe either color or volume changes within the dialysis bogs as they investigate the meaning of diffusion and osmosis.

Materials Components which are provided with this kit, and a list of additional requirements to perform this experiment are listed on page 3.

Extensions

Quantify Results. In all three activities, students should weigh the dialysis bags before and after emersion into the solution baths.

Guidelines for Classroom Discussion

1. Have students become familiar with these vocabulary words: Diffusion permeable dialysis Osmosis semi-permeable concentration gradient

2. Discuss their observations in class.

3. Discuss study questions as a class.

Connections to National Content Standards

1. Students will develop abilities necessary to do scientific inquiry. • Students’ questions will be answered through conduction of a scientific investigation.

2. Students will develop an understanding through inquiry. Students

will: Instructor’s Guide • investigate a working hypothesis. • make careful observations. • interpret results correctly. • understand the difference between the experiment and the control. • identify the variable. • predict experimental outcomes. • formulate explanations from evidence. • develop alternative explanations.

3. Students will use materials and techniques for experimentation and direct investigation of phenomena. • Students will understand and interpret principles involved in the movement of molecules in relation to a concentration gradient.

4. Students will develop an understanding of the principles of diffusion and osmosis. Students will: • understand that molecules are constantly in motion and move down the concentration gradient, or from high concentration to low. • observe that is osmosis, the diffusion of water molecules across a semi-permeable membrane, is from low salt (or high water) to high salt (or low water) concentrations. • understand that pore size determine a membranes permeability to molecules of different sizes. • understand that the principles of osmosis and diffusion of molecules across semi-permeable membranes are involved in the physiological processes of animal systems.

Connections to National Skill Standards

In this experiment students will use procedures that allow for the investigation of the movement of molecules across a semi-permeable membrane.

Students will be able to:

1. Perform all experimental steps accurately. 2. Make careful observations and record and interpret results. 3. Predict experimental outcomes. 4. Share and compare results with other students. 5. Make both qualitative observations and quantitative measure- ments.

Instructor’s Guide Instructor’s

Pre-Lab Preparations

1. Cut the dialysis tubing into smaller pieces - each piece should be about 5 and 1/2 inches long. You should get at least 15 pieces from the tubing provided.

2. Soak the cut tubing in a clean beaker or jar filled with distilled water. Soak the tubing for at least one hour or overnight.

Study Questions and Answers

1. Differentiate between diffusion and osmosis.

Diffusion is the movement of molecules down a concentration gradient from high to low. Osmosis is the movement of water molecules across a semi-permeable membrane from high concentration of water molecules to a lower concentration.

Instructor’s Guide

2. What evidence from this experiment supports the idea that molecules are constantly in motion?

The sizes of the dialysis bags changed and the color of the dialysis bath changed to indicate the movement of molecules and water.

3. What is meant by a semi-permeable membrane?

A semi-permeable membrane is a membrane which allows some materials, such as water, to pass through while rejecting others, such as salt.

4. What determines a membrane s permeability to molecules of different sizes? Give a concrete example from Activity #1.

A membranes pore size will determine what size molecules pass through. The smaller colored dye molecule will cause the dialysis bath to become colored.

5. In Activity #2, what happened to the overall size of a dialysis bag when placed into a salt dialysis bath? Explain.

The bag shrunk in size because the water molecules moved into the salt dialysis bath.

6. Give examples from Activity #3 of different juice pigments that pass through and those that do not pass through a semi-permeable membrane.

Answers will vary based on juices used.

Duplication of this document, in conjunction with use of accompanying reagents, is permitted for classroom/ laboratory use only. This document, or any part, may not be reproduced or distributed for any other purpose without the written consent of EDVOTEK, Inc. Copyright © 1996, 1997, 1998, 1999, 2003, 2007 EDVOTEK, Inc., all rights reserved. EVT 007157AM The Biotechnology Education Company ® • 1-800-EDVOTEK • www.edvotek.com Section V - Reactivity Data Material Safety Data Sheet Stability Unstable Conditions to Avoid ® May be used to comply with OSHA's Hazard Communication Standard. 29 CFR 1910.1200 Standard must be consulted for Stable X Reducing agents specific requirements. Incompatibility Strong oxidizing agents

Hazardous Decomposition or Byproducts IDENTITY (As Used on Label and List) Note: Blank spaces are not permitted. If any item is not applicable, or no information is available, the space must Burning will produce oxides of carbon, nitrogen and sulfur Blue/Green Dye be marked to indicate that. Hazardous May Occur Conditions to Avoid Section I Polymerization Will Not Occur X Manufacturer's Name Emergency Telephone Number (301) 251-5990 Section VI - Health Hazard Data EDVOTEK, Inc. Route(s) of Entry: Inhalation? Telephone Number for information Yes Skin? Yes Ingestion? Yes Address (Number, Street, City, State, Zip Code) (301) 251-5990 Health Hazards (Acute and Chronic) Date Prepared 14676 Rothgeb Drive 02/20/2007 Not considered to be hazardous Rockville, MD 20850 Carcinogenicity: NTP? IARC Monographs? OSHA Regulation? Signature of Preparer (optional)

Signs and Symptoms of Exposure Overexposure may cause eye or skin irritation Section II - Hazardous Ingredients/Identify Information Overexposure may cause eye or skin irritation. Hazardous Components [Specific Other Limits Medical Conditions Generally Aggravated by Exposure Chemical Identity; Common Name(s)] OSHA PEL ACGIH TLV Recommended % (Optional) May cause respiratory irritation. Emergency First Aid Procedures Eyes: Flush continuously with flowing water for at least 15 min. Liquid Green Dye Skin: Wash thoroughly with plenty of water & soap. Respiratory: Remove to fresh air. If distress continues, No Hazardous ingredients present call doctor. Ingestion: If conscious, drink 2 glasses of water to dilute. Call poison control center. Section VII - Precautions for Safe Handling and Use Section III - Physical/Chemical Characteristics Steps to be Taken in case Material is Released for Spilled Boiling Point Specific Gravity (H 0 = 1) Mix material with absorbing compounds. Sweep up and dispose accordingly. For 1% solution N/A 2 N/A

Vapor Pressure (mm Hg.) N/A Melting Point N/A Waste Disposal Method Dispose of waste in accordance with current Federal, State and Local codes and guidelines. Evaporation Rate Vapor Density (AIR = 1) N/A N/A (Butyl Acetate = 1) Precautions to be Taken in Handling and Storing Solubility in Water Maintain good housekeeping to avoid spillage. Avoid breathing mist. Avoid contact with eyes and skin. Completely soluble Store in a dry place away from excessive heat, in original or similar waterproof container. Other Precautions Appearance and Odor Liquid green, slightly sweet odor

N.D. = No data Section IV - Physical/Chemical Characteristics Section VIII - Control Measures Flash Point (Method Used) Flammable Limits LEL UEL N.A. N.A. N.A. Respiratory Protection (Specify Type) NIOSH/MSNA approved Dust Respirator Extinguishing Media Water spray, dry chemicals, foam or carbon dioxide Ventilation Local Exhaust Yes Special Mechanical (General) Other Special Fire Fighting Procedures Firefighters should wear full-face, self contained breathing apparatus and impervious Protective Gloves Impervious gloves Eye Protection Chemical safety goggles protective clothing. Other Protective Clothing or Equipment Eye wash fountain and safety shower should be readily available Unusual Fire and Explosion Hazards None expected Work/Hygienic Practices Wear protective clothing and wash thoroughly after handling.

Section V - Reactivity Data Material Safety Data Sheet Stability Unstable Conditions to Avoid May be used to comply with OSHA's Hazard Communication Stable X EDVOTEK® Standard. 29 CFR 1910.1200 Standard must be consulted for specific requirements. Incompatibility Strong oxidizing agents Hazardous Decomposition or Byproducts IDENTITY (As Used on Label and List) Note: Blank spaces are not permitted. If any item is not Toxic fumes of Carbon Monoxide, Carbon Dioxide, Nitrogenoxide, Sulfur Oxides applicable, or no information is available, the space must Orange Dye be marked to indicate that. Hazardous May Occur Conditions to Avoid Section I Polymerization Will Not Occur X Manufacturer's Name Emergency Telephone Number (301) 251-5990 Section VI - Health Hazard Data EDVOTEK, Inc. Route(s) of Entry: Inhalation? Skin? Ingestion? Telephone Number for information Yes Yes Yes Address (Number, Street, City, State, Zip Code) (301) 251-5990 Health Hazards (Acute and Chronic) Date Prepared May cause irritation 14676 Rothgeb Drive 07/01/03 Carcinogenicity: NTP? IARC Monographs? OSHA Regulation? Rockville, MD 20850 Signature of Preparer (optional) No data Signs and Symptoms of Exposure No data Section II - Hazardous Ingredients/Identify Information Medical Conditions Generally Aggravated by Exposure Hazardous Components [Specific Other Limits No data Chemical Identity; Common Name(s)] OSHA PEL ACGIH TLV Recommended % (Optional) Emergency First Aid Procedures If swallowed, wash mouth with water. Skin contact, flush with water. CAS # 547-58-0 If inhaled, remove to fresh air. This product contains no hazardous components Section VII - Precautions for Safe Handling and Use Section III - Physical/Chemical Characteristics Steps to be Taken in case Material is Released for Spilled Wear SCBA and protective clothing. Mop with Absorbent material. Dispose of properly. Boiling Point Specific Gravity (H 0 = 1) No data 2 No data Waste Disposal Method Vapor Pressure (mm Hg.) No data Melting Point N/A Mix w/ combustible solvent and burn in chemical incinerator equipped with afterburner and Evaporation Rate scrubber. Observe federal, state, and local laws. Vapor Density (AIR = 1) No data (Butyl Acetate = 1) No data Precautions to be Taken in Handling and Storing Wear protective equipment Solubility in Water soluble Appearance and Odor Other Precautions Orange Solution Avoid contact and inhalation

Section IV - Physical/Chemical Characteristics Section VIII - Control Measures Flash Point (Method Used) Flammable Limits LEL UEL Respiratory Protection (Specify Type) NIOSH approved respirator

Local Exhaust Yes Special No Extinguishing Media Water spray, CO2, dry chemical powder or appropriate foam Ventilation No None Mechanical (General) Other Special Fire Fighting Procedures Protective Gloves Eye Protection Wear SCBA and protective clothing to prevent contact with skin and eyes Chemical resistant splash resistant Other Protective Clothing or Equipment Unusual Fire and Explosion Hazards None Emits toxic fumes under fire conditions. Work/Hygienic Practices Avoid contact and inhalation