Application of Exothermic Reaction and Endothermic Reaction in Daily Life

 Examples of Applications of Exothermic Reactions in Everyday Life Hot can Hot food or beverages prepared without external heat Termite reaction Welding of railway tracks Combustion of fuel Used for cooking food

 Examples of Applications of Endothermic Reactions in Everyday Life Gel pads Relieves fever Self cooling beverages Beverages in cold cans without storing in refrigerators or using ice Sorbet The tongue feels cold when the sorbet is put in the mouth

Fuel Value

 Definition of fuel value The amount of heat energy released when one gram of fuel is completely burnt in excess oxygen
 Fuels are substances that burn in the air to produce heat energy. Each fuel has different heat of combustion. The unit for fuel value is $$\text{kJ g}^{−1}$$. The fuel value can also be determined with the heat of combustion of substances.
 Formula to calculate fuel value $$\text{Fuel value } =\\ \dfrac{\text{Heat of combustion of subtance}}{\text{Molar mass of substance}}$$

 Example of calculation Question The heat of combustion of octane, $$C_8H_{18}$$ is $$-5\,500 \text{ kJ mol}^{−1}$$. Calculate the fuel value of octane, $$C_8H_{18}$$. [Relative atomic mass: H = 1, C = 12] Solution Molar mass of octane, $$C_8H_{18}$$. $$=(8 \times 12)+(18 \times1)\\ =96+18\\ =114\text{ g mol}^{−1}$$   Complete combustion of 114 g of octane, $$C_8H_{18}$$ releases 5 500 kJ of heat.  Therefore, combustion of 1 g of octane, $$C_8H_{18}$$ is as follows; $$=\dfrac{5\,500 \text{ kJ mol}^{−1}}{114 \text{ g mol}^{−1}}\\ =48.2\text{ kJ g}^{−1}$$ The fuel value of octane, $$C_8H_{18}$$ is $$48.2\text{ kJ g}^{−1}$$.

 Fuel Fuel value ($$\text{ kJ g}^{−1}$$) Wood 20 Methane 27 Charcoal 30 Ethanol 30 Petrol 34 Kerosene 37 Natural gas 50 Hydrogen 143

 Choice of fuel Fuel value Cost of fuel Availability and source of substance Effects of the fuel on the environment

Application of Exothermic Reaction and Endothermic Reaction in Daily Life

 Examples of Applications of Exothermic Reactions in Everyday Life Hot can Hot food or beverages prepared without external heat Termite reaction Welding of railway tracks Combustion of fuel Used for cooking food

 Examples of Applications of Endothermic Reactions in Everyday Life Gel pads Relieves fever Self cooling beverages Beverages in cold cans without storing in refrigerators or using ice Sorbet The tongue feels cold when the sorbet is put in the mouth

Fuel Value

 Definition of fuel value The amount of heat energy released when one gram of fuel is completely burnt in excess oxygen
 Fuels are substances that burn in the air to produce heat energy. Each fuel has different heat of combustion. The unit for fuel value is $$\text{kJ g}^{−1}$$. The fuel value can also be determined with the heat of combustion of substances.
 Formula to calculate fuel value $$\text{Fuel value } =\\ \dfrac{\text{Heat of combustion of subtance}}{\text{Molar mass of substance}}$$

 Example of calculation Question The heat of combustion of octane, $$C_8H_{18}$$ is $$-5\,500 \text{ kJ mol}^{−1}$$. Calculate the fuel value of octane, $$C_8H_{18}$$. [Relative atomic mass: H = 1, C = 12] Solution Molar mass of octane, $$C_8H_{18}$$. $$=(8 \times 12)+(18 \times1)\\ =96+18\\ =114\text{ g mol}^{−1}$$   Complete combustion of 114 g of octane, $$C_8H_{18}$$ releases 5 500 kJ of heat.  Therefore, combustion of 1 g of octane, $$C_8H_{18}$$ is as follows; $$=\dfrac{5\,500 \text{ kJ mol}^{−1}}{114 \text{ g mol}^{−1}}\\ =48.2\text{ kJ g}^{−1}$$ The fuel value of octane, $$C_8H_{18}$$ is $$48.2\text{ kJ g}^{−1}$$.

 Fuel Fuel value ($$\text{ kJ g}^{−1}$$) Wood 20 Methane 27 Charcoal 30 Ethanol 30 Petrol 34 Kerosene 37 Natural gas 50 Hydrogen 143

 Choice of fuel Fuel value Cost of fuel Availability and source of substance Effects of the fuel on the environment