# Lab Write Up

## Introduction

Osmosis is the transfer of a liquid through a semipermeable membrane that does not allow dissolved solids (solutes) to pass. In this experiment you will measure diffusion of small molecules through dialysis tubing, a selectively permeable membrane. Small solute molecules and water molecules can move freely through a selectively permeable membrane, but larger molecules will pass through more slowly, or perhaps not at all.The purpose of this experiment is to see if the mass changes after the different solutes sit over night. The independent variable is the solution. The dependent variable is water mass. The control variables are are the solution, dialysis bags, and amount of solution.

## Hypothesis

If the water exits the bag then the mass will go down.

## Materials

• 3 dialysis bags
• 3 strings
• Drinking water
• Measuring cups
• Diet soda
• Clear Soda
• Regular soda
• Scale

## Procedure

1. Tie bottom of bag with string & fill with 10 ml of drinking water, then tie top

2. Measure mass of bags

3. Add 200 ml of solution to cup. And label each cup.

4. Add one bag to diet soda, one bag to regular soda, one bag to clear soda.

5. Leave sitting overnight

6. Measure each bag in the morning

7. Collect data

8. Record data in table

## Table

Bag 1: Before: 16.7 g After:

15.4 g

Bag 2: Before: 16.1 g After:

12.6 g

Bag 3: Before: 22.3 g After:

18.5 g

## Conclusion

In conclusion the hypothesis was if the water exits the bag then the mass will go down. The lab results show that this is true. Water exited the bag and the mass in bag one went down 1.3 grams, in bag two it went down 3,5 grams, and in bag 3 it went down 3.8 grams. This lab shows that the dialysis bag was semi-permeable to the solute.