Author

Nadia Chocron is a teacher at Lindero Canyon Middle School

## Principles

The ideal gas law states that pressure(volume)/temperature is constant.  As pressure increases, temperature increases.  Also, as volume decreases, temperature will increase.  If pressure and volume decrease quickly, it will result in a sudden over-heating of the gas called adiabatic heating.

## Standards

8.3.e

Students know that in solids, atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; and in gases the atoms and molecules are free to move independently, colliding frequently.

## Materials needed

Small pieces of cotton or kindling

## Procedure

1.  Place a small amount of cloth or tinder into tinder hole.

2.  Replace the piston into the top of the piston sleeve.

3.  Rapidly depress piston into piston sleeve.

4.  If it is dark enough, you will see a flash.

5.  Remove the piston from the sleeve carefully.

6.  Remove tinder and place on tinder bundle to start a fire.

## Explanation

Adiabatic heating occurs when the pressure and volume of a gas are both decreased quickly resulting in a sudden increase in temperature.  It is a dramatic example of Gay Lussac's Law which states that there is a direct relationship between temperature and pressure.  As pressure increases, temperature also increases.  Due the sudden pressure change, the temperature increases dramatically resulting in a spark.

## Questions

1. What is the relationship between pressure and volume?
2. What is the relationship between pressure and temperature?
3. Why did the tinder spark?

## Everyday examples of the principles illustrated

• Using a bicycle pump - when you pump air into the bike pump, the barrel of the pump will feel warm to the touch
• diesel engines - the engines rely on adiabatic heating to ignite the fuel

## Photos

Here is the fire syringe that I have.  It was ordered from Arbor Scientific.