Understanding Chemical Reactions

Chemical Reactions

• Substances transform into entirely new substances with different characteristics.
• Chemical reactions occur when atoms and molecules rearrange which results in products.
• The Collision Theory says that chemical reactions needs collisions between particles.
• For a chemical reaction to complete, particles must collide correctly and with enough energy.
• Reactions happen at varying speeds, from explosions to the slow rusting of iron.

Factors Affecting Reaction Rates

• Nature of Reactants: Different substances react at different rates due to varied activity.
• Concentration of Reactants: Higher concentration leads to more particle collisions, increasing reaction rate.
• Temperature: Higher temperature increases kinetic energy, speeding up particles and collision frequency. A 10°C increase can double or triple the reaction rate.
• Catalysts and Inhibitors: Catalysts speed up reactions without being consumed; inhibitors slow them down. Biological catalysts are called enzymes.
• Surface Area: Increasing the surface area, especially of solids, increases the reaction rate.
• Pressure: Increasing pressure, especially for gases, increases reaction rates by bringing particles closer.

Chemical Reactions in Daily Life

• Occur constantly, such as in food decay, plant growth and in our own bodies.

Food Spoilage

• Action of bacteria or fungi, which happens rapidly without methods to reduce it.
• Prevented by: Lowering the temperature of food or adding inhibitors.
• Low temperatures (-5°C to 30°C) slow bacteria and mold activity, preventing decay.

Fermentation

• Metabolic process that uses enzymes to chemically change substances.
• Extracts energy from carbohydrates without oxygen.

Biodegradable Waste

• Organic matter is broken down by microorganisms, composting, or anaerobic digestion.

Importance of Chemical Reactions

• Central to processes in the universe, including plant growth and nutrient recycling.
• Nutrient cycle: The use, movement, and recycling of nutrients within the environment. Carbon, oxygen, hydrogen, phosphorus, and nitrogen are essential.
• Chemical reactions break and form bonds, and involves energy.
• Endothermic reactions absorbs energy, while exothermic reactions releases energy which follows the law of the conservation of energy.
• Responsible for biological processes like reproduction, digestion, growth, and thought.
• Elements that join together are called molecules. An oxygen molecule has two oxygen atoms.
• Chemical reactions are responsible for the formation of chemical makeup of stars and fuels life on Earth.
• Reactions are key to understanding matter's properties, explaining natural events, and driving scientific inquiry.
• They help solve crimes, understand ancient life, and explore other planets.
• Fire is a fundamental chemical reaction.

Chemical Industry Product Categories

• Basic chemicals, specialty chemicals, and consumer chemicals.
• Basic chemicals: Used by the industry or sold to other industries for further processing (e.g., acetic acid). Divided into petrochemicals, polymers, and basic inorganics.
• Petrochemicals and polymers: Large amount produced from petroleum and are key to creating varied polymers.
• Basic inorganics: Low-cost chemicals used in agriculture like fertilizers.
• Specialty chemicals (effect chemicals): Chemicals that provide various effects for other industries e.g textiles, paint and engineering.
• Consumer chemicals: Directly sold to the public; detergents, soaps, and toiletries.