Factors which affect reaction rate

The rate of a chemical reaction depends on several factors that influence how frequently and effectively particles collide.

1. Nature of Reactants

• More reactive substances react faster.
• Metals like Mg react faster than less reactive metals like $Cu.$
• Inorganic reactions are usually faster than organic reactions.

2. Concentration of Reactants (in solutions) & Pressure (in gases)

• Higher concentration → More frequent collisions → Faster reaction.
• Increased gas pressure → Particles are closer together → More collisions → Faster reaction.

3. Surface Area of Solid Reactants

• Larger surface area → Faster reaction (more particles are exposed for collisions).
• Powders react faster than lumps because they have more surface area.

4. Temperature

• Higher temperature → Faster reaction because: ✅ Particles move faster and collide more often. ✅ More particles have enough energy to overcome activation energy $(Ea).$

5. Presence of a Catalyst

• Catalysts speed up reactions by lowering the activation energy.
• They provide an alternative reaction pathway with lower energy requirements.
• Positive catalysts increase reaction rate, while inhibitors slow it down.

Key Takeaways

✅ Reaction rate depends on reactant properties, concentration, pressure, surface area, temperature, and catalysts.

✅ Higher concentration, temperature, or surface area increases reaction speed.

✅ Catalysts lower activation energy, making reactions occur faster.