Developing a New, Improved Cold Pack

based on 5 ratings
Author: Muriel Gerhard



High School

Difficulty of Project



$10 - $15

Safety Issues

Wear Safety glasses and apron when handling chemicals. Do not mix the three chemicals used in this experiment.

Material Availability

The materials, equipment and the chemicals can be found in any high school lab.

Approximate Time Required to Complete the Project

One week. This includes collection, recording and analysis of data, summary of results and completion of bibliography.


To determine (a) which of the following chemicals, ammonium chloride, calcium chloride or  sodium chloride  would be best for lowering the temperature of water in a cold pack and (b) if the amount of the best chemical affects its use in the cold pack.

Materials and Equipment Required

  • 1 scoopful of ammonium chloride
  • 3 teaspoons
  • 1 scoopful of calcium chloride
  • 3 stirrers
  • 1 scoopful of sodium chloride
  • 1 graduated cylinder
  • 10 small plastic cups
  • 1 thermometer
  • water
  • labeling dots
  • a balance
  • 1 pair of vinyl gloves
  • clock or watch with a second hand
  • paper towels
  • splash-proof safety goggles and apron

All of the above materials and equipment are readily available for use in any high school chemistry lab. Additional chemicals can be purchased from companies such as Chem Scientific, a leading supplier of inexpensive apparatus, chemicals and materials for science education.


Background Information

We can make our own cold pack by placing water in the freezer and producing ice cubes. However there are chemical reactions we can produce to make things cold. Certain chemicals when dissolved in water give off heat, while others become cold. These chemicals can be used in hot or cold packs. Reactions that absorb heat from the environment are called endothermic reactions. These chemicals can be used in hot or cold packs. Cold packs can be used to reduce swelling from a bruise or injury. The design and improvement of the cold pack is an excellent example of the practical application of scientific knowledge. Students profit greatly when they view their knowledge and exploration of knowledge in the context of practical applications to daily life.

This science fair experiment also serves to acquaint students with the essential processes of sciencing such as the importance of the use of a control, of identifying dependent and independent variables, of data collection, of pictorial and graphic presentation of data and of being able to make better judgments as to the validity and reliability of their findings. They take on the role of scientists and in the process they learn to act as one.

Research Questions

  • What is a simple cold pack?
  • What is a chemical cold pack?
  • How are cold packs used?
  • What is an endothermic reaction?
  • What are hot packs?
  • What is an exothermic reaction?
  • On the average, how long do cold packs last?
  • What are the common uses of each of the chemicals, sodium chloride, ammonium chloride and calcium chloride?
  • Why shouldn`t we mix all three?
  • Are there other chemicals used in cold packs? If so, what are they?
Add your own comment