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< h1 id = "study-topic-title" style = "margin-bottom: 1rem;" > Exothermic & Endothermic < div id = "study-notes" class="study-content" style = "text-align: left; margin: 2rem 0; line-height: 1.6;" >

1. Exothermic Reactions

Reactions that release energy to the surroundings, usually as heat. Enthalpy change (ΔH) is negative. Examples: Respiration, Combustion.

2. Endothermic Reactions

Reactions that absorb energy from the surroundings. ΔH is positive. Examples: Photosynthesis, Decomposition of CaCO₃.

3. Bond Energy

Breaking bonds requires energy (Endothermic), while forming bonds releases energy (Exothermic). The net difference determines the overall heat change.