What is caloric value and ignition …

Calorific value: The heating value or calorific value of a substance, usually a fuel or food, is the amount of heat released during the combustion of a specified amount of it. The calorific value is a characteristic for each substance. It is measured in units of energy per unit of the substance, usually mass, such as: kcal/kg, kJ/kg, J/mol, Btu/m³.

Ignition temperature

• The lowest temperature at which a substance catches fire and undergoes combustion liberating heat and light is called ignition temperature.
• In other words it is the minimum temperature at which a combustible substance such as air or gas, must be heated up prior to burning in the absence of any source of the heat. This temperature plays a key role in determining the safety criterions for low volatile products such as diesel oil, lubricating oil, and fuel oil.
• We have already observed that matchstick gets ignited as soon as we strike it against the matchbox whereas it takes a lot of time to ignite a mosquito repellent.