Chemical Reactions

01 Conservation of Mass

Atoms cannot be created or destroyed in chemical reactions - they are just rearranged. The total mass of reactants always equals the total mass of products. Lavoisier established this in the 1780s, overturning the phlogiston theory.

02 Energy in Reactions

Exothermic reactions release energy (combustion, explosions). Endothermic reactions absorb energy (dissolving ammonium nitrate, photosynthesis). Activation energy is the minimum energy needed to start a reaction - catalysts lower this without being consumed.

03 Equilibrium and Le Chatelier

Reversible reactions reach a state of dynamic equilibrium where forward and reverse reactions occur at equal rates. Le Chatelier's Principle: if you disturb an equilibrium (change concentration, temperature, pressure), the system shifts to counteract the change. This governs industrial processes like the Haber process for making ammonia.

04 Key Facts

→The Haber process (N₂ + 3H₂ → 2NH₃) feeds roughly half the world's population by making fertiliser.

→A catalyst can speed up a reaction by a factor of 10 billion without being consumed.

→Chemiluminescence (glow sticks) produces light without heat via a chemical reaction.

🔗 Nuclear Connection

Chemistry and nuclear physics are deeply intertwined. Explore the nuclear side of ChemHub's parent site:

☢️ Nuclear Elements 🏥 Radiation & Health 🔋 Fuel Cycle