Proofread the following text carefully and correct the five spelling errors. Within a small chamber, an internel combustion engine combines a precisely measured mix of fuel (typically petrol or diesil) and air. Once ignited, this explosive combinasion causes an expansion of hot, presurised gases to exit the chamber, typically via pistons or a turbine. The chemical energy is converted, although often not very eficiently, into mechanical energy which can then be used to power motors and drive machines.