How Dense Is the Incredible Edible Egg?

Objective

The objective is to measure the difference in density of an egg before and after boiling it.

Please Note: It has come to our attention that the volume measurements required for this project need to be more precise than the procedure currently allows for. We are in the process of re-writing this project to address this problem. Meanwhile, if you have already started this project you can proceed by comparing the mass of each egg when raw versus boiled. Be sure to use a scale that is accurate to 0.1 grams.

Introduction

An egg is a cell, which means that it has many parts and pieces scattered and organized within it; the egg is a heterogeneous mixture. Eggs, like people, are different from one another in fairly small ways. Yet on average, all eggs are the same, regardless of which chicken they are created by. Of course, some may have slightly larger yolks, sometimes twins are born, and all have different DNA, but overall they are the same—much like newborn infants are different from each other due to their mother's diet, ages, etc. but are generally the same.

When an egg is boiled, some of the air in its air pockets escapes and is replaced by water.

The shell of the egg is made of calcium carbonate with small amounts of magnesium carbonate, calcium phosphate, and other organic matter, including protein.

The white of the egg changes over time. A freshly laid egg has more carbon dioxide, while an older egg has lost some it through the pores in the shell. So, the pH level of the egg changes, depending on how much carbon dioxide is left. Because eggs lose carbon dioxide and water with time, that causes the air pockets to grow, and they lose weight.

The yolk has all the fat in the egg and has slightly less than half of the protein of the egg. With the exception of riboflavin and niacin, it has more of the egg's vitamins than the white. It also holds more phosphorus, manganese, iron, iodine, copper, and calcium. All of the egg's vitamins A, D and E, and zinc are in the yolk.

Overall the egg is made of the same stuff as we are, sort of.

Boiling an egg is a chemical change, because hydrogen bonds break when the egg is boiled.

Terms, Concepts and Questions to Start Background Research

Before starting your experiment you should be familiar with the following concepts:

• volume
• mass
• density

It would also benefit you to familiarize your self with the terms in bold in the Introduction.

Bibliography

• Definition and Exercise in Density:
  http://www.nyu.edu/pages/mathmol/textbook/density.html
• General Chemistry:
  http://library.thinkquest.org/2923/index.html
  http://www.chem4kids.com

Materials and Equipment

• 1 digital scale (can use the digital scale at the post office or the grocery store)
• Water
• 800 ml graduated cylinder (can be purchased as part of a childrens chemistry set in toy stores, at a local teacher's store, online, or substituted with gradated measuring cups for cooking with fine gradations)
• stove
• 6–9 eggs (one size optional)
  • 3 jumbo
  • 3 extra large
  • 3 medium
• 1 pot
• oven mitts
• food or egg coloring (for numbering the eggs)

Experimental Procedure

1. Number each egg.
   1. Use an edible dye, like the ones for easter egg or food coloring.
   2. You'll need the numbers to identify the eggs before and after boiling.
2. Weigh each egg.
   1. Turn on scale and re-zero (tare) it so that the starting point is 0.
   2. Put the egg on the scale. (Eggs roll easily. If your egg won't stay put on the scale, make an egg holder out of a section of egg carton. You should re-zero (tare) the scale with the empty egg holder in place, or weigh the empty egg holder alone and subtract this weight from the value of egg + egg holder.)
   3. Record weight in your lab notebook. (If you use a data table, it will help to keep your results organized. See the sample data table below.)
   4. For more details on how to properly use a scale see Chemistry Lab Techniques.
3. Measure the volume of each egg.
   1. Fill an 800 ml graduated cylinder to 500 ml with water (initial volume). Measure the water level by reading the value at the bottom of the meniscus (the curved surface of the water, due to surface tension).
   2. Carefully tilt the cylinder and slide the egg into the water.
   3. Measure the volume of the water + egg (final volume) and record it in your lab notebook.
   4. Calculate the volume of the egg by subtracting the initial volume from the final volume. Record the value in your lab notebook.
4. Boil eggs.
   1. Fill a pot with water.
   2. Turn on the stove and put the pot on top of it.
   3. Immediately put the eggs into the pot and wait 5–10 min.
   4. Wear oven mitts for this step! Take the pot off the stove, and put it in the sink. Slowly run cold water into the pot to cool down the eggs.
5. After the eggs have cooled, measure the density of the boiled eggs, following the procedures above for weighing and measuring the volume.
6. Graph the results and compare the density before and after boiling.

Variations

• For more science project ideas in this area of science, see Chemistry Project Ideas

Credits

Last edit date: 2005-10-19 19:32:47