Hd-2 The Fire Syringe
Aim
To demonstrate the generation of heat during compression of air.
Apparatus
- Fire syringe kit
- Match heads or small pieces of tissue
Fire Syringe Apparatus.
Description
The demonstration consists of placing within the combustion chamber scrapings from a match head. Forcing the piston rapidly down compresses the air adiabatically and raises its temperature to approximately 1000°K whereupon the match head ignites. It is possible to use a small piece of tissue paper instead of the match head but the demonstration is difficult. In a typical compression the volume decreases by a factor of 20. Both nitrogen and oxygen, the primary constituents of air have γ=1.4
The equation for the adiabatic gas is given by
Where Cp is the specific heat at constant pressure of gas
Cv is the specific heat at constant volume of gas
If Ti=300°K
Tf=300.(20)0.4
Which yields T=994°K