Chemistry of combustion and arson Flashcards
Four Aspects of Combustion
- Thermodynamics
- Kinetics
- Heat Transfer
- Mass Transfer
What is high explosive?
High explosives detonate at a rate greater than the speed of sound.
What is low explosive?
Low explosives are mixtures of chemicals that burn very rapidly, but subsonically (as opposed to supersonically), meaning that they “deflagrate.”
What is complete combustion?
In complete combustion, when a hydrocarbon burns in oxygen, the reaction will yield mainly CO2 and water and NO2 as minor products.
What is incomplete combustion?
incomplete combustion, some of carbon is converted to CO.
First Law of Thermodynamics states
Energy can neither created or destroyed, but it can change form.
Second Law of Thermodynamics states
The second law of TD relates to entropy and it states that the entropy of the Universe increases i.e. In any spontaneous process disorder of the system increases.
Free Energy change in any reaction including combustion is defined as
ΔG⁰ = ΔH⁰ - TΔS⁰
Work is composed of
pressure-volume (PdV) and heat (q).
What does ΔG measures ?
The amount of work done by the system in a spontaneous reaction
What does ΔG measures ?
The amount of work done by the system in a spontaneous reaction
What does ΔG measures ?
The amount of work done by the system in a spontaneous reaction
What is the fuel-to-oxidizers (F/O) ratio?
The fuel to oxidizers (F/O) ratio determines the effectiveness of combustion reaction and the amount of heat evolution (heat of combustion reaction).
What is Oxygen balance?
Oxygen balance refers to the amount of oxygen contained in a compound relative to the amount needed to convert all the carbon to carbon dioxide and the hydrogen to water.
