Osmosis and Diffusion (Mahya Babaie)


Research Question and Hypothesis

How Do Hypotonic, Hypertonic, and Isotonic Solutions Affect the Water Movement of a Cell? 

Standards

7th Grade California Content Standard

  •            Students know cells function similarly in all living organisms. 
  •            Scientific progress is made by asking meaningful questions and conducting careful  
                     investigations.       
  •            Students should develop their own questions and perform investigations.

Introduction:

Osmosis is the diffusion of water through a selectively permeable membrane. Water will diffuse into a cell or out of a cell depending on the concentration of water on each side of the membrane. Water will alway move from an area of greater concentration to an area of lesser concentration.

Experimental Design:


           Day 1: 

1. Observe three eggs.  Record your observations. 
2. Use the triple beam balance to find the mass of your eggs. Record. Use the measurement tape to measure the circumferences. Record. 
3. Use the masking tape to label your beakers. 
4. Pour 200 mL of vinegar into one of the beaker. 
5. Gently set your eggs into the beaker. 
6. Set the beaker aside for 24 hours. 

Day 2:

1. Observe the eggs in the beaker.  Record your observations. 

 2. Use the spoon to remove the eggs from the beaker.  

3. GENTLY rinse the eggs and find its masses. Record.

4. Using the graduated cylinder, measure the amount of vinegar left in the beaker.  Record. 
5. Rinse the beaker. 
6. Pour 200 mL of corn syrup into one beaker; 200 ml of vinegar in another beaker and 200 ml water in the third beaker.  
7. GENTLY place one egg into each of these three beakers 
8. Set the beakers aside. 



Day 3:

1. Observe the egg.  Record your observations. 
2. Use the spoon to remove the egg from the beakers. The egg is still very, very fragile. 
3. GENTLY rinse the egg and find its mass. Record. 
4. Using the graduated cylinder, measure the amount of liquid in the beaker.  Record. 


           Day 4:

1. Observe the egg.  Record your observations. 

2. Use the spoon to remove the egg from each beakers. The egg is still very, very fragile. 

3. GENTLY rinse the egg and find its mass. Record. 

4. Using the graduated cylinder, measure the amount of liquid in each beakers. Record

Independent variable

Time

Dependent variables

Egg's mass  

Series

 Study the mass and size of eggs (dependent variable) as a function of time (independent variable) at various timeline (series). 

Constants and Controls

We have a control egg (egg in water ) so we can compare the experimental eggs to it. The temperature is held constant all the time.  

Materials

1. Few raw egg (3) 

2. Large beakers (3) 

3. Vinegar 

4. Graduated cylinder 

5. Spoon 

6. Corn syrup 

7. Distilled water 


Procedures

Refer to experimental design. 

Sample data and graphs

Day 1

 
   Egg 
  Mass 
    (g)

  Observation
about the size  
 After vinegar  95g The egg seems to be larger.
 After the 
corn syrup 
 66 g You can tell the egg is a little smaller.
 After the water  104 g The size of the egg has increased. 

Day 2 

  Egg 
Mass
(g)

Observation 
about the size
 After vinegar 104 g The egg keeps getting larger. 
 After the corn syrup  44 g The egg is shrinking. 
 After the water  111 g  The egg is keep getting larger. 

Day 3 

  Egg 

Mass (g)

Observation 
about the size
 After the vinegar 109 g The egg is larger than yesterday. 
After the corn syrup  41 g This egg keeps getting smaller. 
 After the water 112g  This will explode soon!

Day 4

  Egg 
Mass (g)
 Observation
about the size 
 After the vinegar 105 g The skin is very thin and the size has increased since yesterday. 
 After the corn syrup 39 g This egg lost its shape. 
After the water  113 g  Almost as twice as the original size. 

Include raw data and graphs.  Make certain to include units in all measurements, titles on all graphs, and labels on all axes. 

Make a LINE GRAPH to compare the change in the egg’s mass as the 

type of liquid changed.  Remember title & labels.



Analysis & Conclusions

Analyze the data and draw conclusions relevant to your research question and hypothesis.

 

1. Based on your observations, what effect did the vinegar have on the egg? 

 

 

2. Was the vinegar (Day 1) a hypotonic, hypertonic or isotonic solution? ______________ 

Explain how your data and observations support this conclusion. 

 

 

3. Was the syrup (Day 2) a hypotonic, hypertonic or isotonic solution? ________________ 

Explain how your data and observations support this conclusion. 

 

 

4. Was the water (Day 3) a hypotonic, hypertonic, or isotonic solution? ________________ 

Explain how your data and observations support this conclusion. 

 


Photos & Movies

YouTube Video


References


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