In photosynthesis reactions or melting ice reaction that the system absorbs energy from surround. Some examples for Endothermic reactions are melting ice cubes, conversion of frost to water vapor, Urea in water and Ammonium Chloride (contain in Battery) in water.

Example of Endothermic Reaction

Endothermic reactions are chemical reactions that absorb heat from their surroundings. In these reactions, the energy of the reactants is lower than the energy of the products, resulting in the absorption of thermal energy. This leads to a decrease in the temperature of the surroundings.

One example of an endothermic reaction is the reaction between ammonium nitrate and water. This reaction is commonly used in instant cold packs, where a rapid decrease in temperature is desired.

Reaction:
NH4NO3 + H2O → NH4+ + NO3- + H2O

Explanation:
1. The reaction involves the dissolution of ammonium nitrate (NH4NO3) in water (H2O).
2. As the solid NH4NO3 dissolves in water, energy is required to break the ionic bonds between the NH4+ and NO3- ions in the crystal lattice.
3. This breaking of bonds requires an input of energy, which is obtained from the surrounding environment.
4. As a result, the reaction absorbs heat from its surroundings, causing a decrease in temperature.
5. The dissolution of NH4NO3 is an endothermic process because it requires the absorption of thermal energy to proceed.
6. The dissolved NH4+ and NO3- ions remain in the solution and are surrounded by water molecules.

Significance:
The endothermic reaction between ammonium nitrate and water is utilized in instant cold packs. These packs consist of two separate compartments, one containing solid NH4NO3 and the other containing water. When the pack is squeezed, the water compartment ruptures, allowing the water to come into contact with the solid NH4NO3.

Uses of Instant Cold Packs:
1. In sports injuries: Instant cold packs are commonly used to provide immediate cold therapy for reducing pain and inflammation in sports injuries.
2. First aid: They are also used in first aid situations to alleviate pain and swelling caused by strains, sprains, and bruises.
3. Medical applications: Instant cold packs are used in medical settings for localized cooling in surgical procedures or to lower body temperature in cases of hyperthermia.

Overall, the endothermic reaction between ammonium nitrate and water is a significant example of how heat can be absorbed from the surroundings, resulting in a decrease in temperature. This reaction has practical applications in the form of instant cold packs, providing a convenient and effective method for achieving rapid cooling.

Conversion of frost to water vapor