Exercise 1.2: Make a Naked Egg


Experiment Time - Make a Naked Egg

In this experiment you will be observing how a weak acid can dissolve an egg shell. Egg shells are composed of a material called calcium carbonate. The weak acid we will be using is white vinegar.

This experiment is meant to simulate the effects of acid rain on the environment. Acid rain is created when gases from factories and industry go into the air and mix with the clouds. The reactions can contaminate the rain that falls on the Earth below.

The vinegar in this experiment will represent acid rain. Vinegar is actually more acidic than most acid rain that falls on Earth, but the effects of acid rain over time accumulate and have a stronger affect as months and years go by.

Egg shell is mostly composed of calcium carbonate. This organic material forms egg shells, but also a lot of other materials on Earth. Chalk is made of calcium carbonate. So are ocean coral and some shellfish shells. Building materials like limestone and marble also contain a lot of calcium carbonate.

By examining the effects of vinegar on an egg shell we can draw some conclusions about how acid rain will affect our environment.

The Experiment

Problem: Can egg shells be dissolved in a weak acid?

Materials:

  • 1 raw egg (any size)
  • 1 cup or glass large enough to totally submerge the egg
  • Enough white vinegar to fill the cup two times

Experimental Design: One raw egg of any size will be used for this experiment. The egg will be submerged in vinegar, a weak acid, for at least 48 hours. In this case the manipulated variable is the environment that the egg was in. The responding variable is the condition of the egg after 48 hours in the weak acid environment. Do not eat your naked egg when the experiment is finished.

Procedure

1. Carefully place one raw egg into your cup or glass.

2. Pour white vinegar into the cup until the egg is totally submerged.

3. Leave the cup in a safe place and do not stir or disturb it. It does not need to be refrigerated.

4. After approximately 4 hours has passed, look inside the cup and record your observations in the Experimental Data section.

5. After approximately 12 hours has passed, look inside the cup and record your observations in the Experimental Data section.

6. After 24 hours has passed, carefully pour the vinegar out of the cup, leaving the egg inside. Record your observations in the Experimental Data section.

7. Fill the cup with vinegar again and leave it to sit for another 24 hours.

8. After 48 hours has passed, carefully pour the vinegar out of the cup. You may take the egg out of the cup and handle it carefully. Record your observations in the Experimental Data section.

9. Answer the questions in the Analysis section.

Your final assignment submission should include the completed Experimental Data and Analysis sections.

Experimental Data

Time of Observation
What do you observe?

Before Experiment

Describe what the egg looks and feels like before placing it into the vinegar.

Time Mark: 0 hours

What did you observe when you dropped the egg into the vinegar?

Time Mark: 4 hours

What do you observe when you look into the cup?

Time Mark: 12 hours

What do you observe when you look into the cup?

Time Mark: 24 hours

What do you observe when you look into the cup?

Time Mark: 48 hours

What do you observe when you look into the cup?

After Experiment

Remove the egg and handle it carefully. Describe what the egg looks and feels like now.

 

Analysis

1. What evidence did you see in the experiment that indicated the acid was dissolving the shell?
2. Between the 4 and 12 hour mark what changes did you observe?
3. Between the 12 and 24 hour mark were there any changes? Describe them.
4. Between the 24 and 48 hour mark were there any changes? Describe them.
5. Once the shell was totally dissolved, why was the egg still held together?
6. After conducting this experiment, what conclusions can you draw about the effect of acid rain on the environment?

Further Experimentation and Research

If this experiment has made you curious, change some of the variables in the experiment and see how they affect the outcome of the experiment.

For example:

  • Try the experiment using cola (Pepsi, Coke, etc.) instead instead of vinegar. 
  • Try the experiment using different types of vinegar (apple cider, red wine, rice, etc.)
  • See osmosis at work. Take your naked egg and put it into a salt water solution. See how the egg "cell" changes after a few hours immersed in the salty water.
  • Put some food colouring into your vinegar solution. You can create a dyed naked egg.