GCSE Chemistry Revision "Exothermic and Endothermic Reactions

Exothermic Reactions

• Definition: Exothermic reactions release energy into the surroundings, causing an increase in temperature of the surroundings.

• Example: Wood burning (combustion) is a common exothermic reaction.

• Other Examples:

  • Certain oxidation reactions

  • Neutralization reactions

• Energy Profile:

  • In an exothermic energy profile, the products have lower energy than the reactants, indicating energy has been transferred to the surroundings.

  • The energy difference (ΔE) between reactants and products represents the energy released.

• Applications:

  • Utilized in hand warmers.

  • Used in self-heating cans for food or drink.

Endothermic Reactions

• Definition: Endothermic reactions absorb energy from the surroundings, leading to a decrease in temperature of the surroundings.

• Example: Thermal decomposition, which will be discussed in detail in future videos.

• Energy Profile:

  • In an endothermic energy profile, the products have higher energy than the reactants, indicating energy has been absorbed.

  • The energy difference (ΔE) between reactants and products indicates the energy absorbed by the reaction.

Activation Energy

• Definition: The minimum amount of energy required for reactants to collide and undergo a reaction.

• Importance: Reactions occur only when particles have sufficient energy to collide.

• Energy Profile Representation:

  • Activation energy is illustrated as the energy difference from the reactants to the peak of the energy profile curve (activation peak).

  • This holds true for both exothermic and endothermic reactions.