Chemical Reactions and Their Impact on Industry
Classified in Chemistry
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Chemical Change vs. Phase Change
Chemical change: Produces new substances that didn't exist before.
Phase change: The substance remains the same before and after the process.
Dissolving: It is only a homogeneous mixture; no new substances appear.
Identifying Chemical Changes
How do we know if a chemical change is occurring?
- Gas release: Gases may not be visible; we identify them by bubbles in a liquid.
- Color change
- Thermal energy change
- Energy release as light
Understanding Chemical Reactions
A chemical reaction occurs when the starting substances, called reactants, transform into other new substances, called products.
The appearance of new substances is due to the rearrangement of the reactant's atoms, forming the products. The information about a chemical reaction is written as a chemical equation.
Chemical Equations and Formulas
Water: H2O Methane: CH4
Carbon dioxide: CO2 Ammonia: NH3
Oxygen: O2 Sodium chloride: NaCl
Hydrogen: H2 Hydrochloric acid: HCl
Nitric oxide: NO Nitrogen: N2
Fundamental Laws of Chemical Reactions
The law of conservation of mass: In a chemical reaction, matter is neither created nor destroyed, only transformed. Therefore, the sum of the masses of the reactants is equal to the sum of the masses of the products of the reaction.
The law of definite proportions: The masses of the reactants and products maintain a constant proportion during chemical reactions.
Synthesis Reactions and the Chemical Industry
A synthesis reaction aims to obtain or manufacture a substance; it occurs naturally.
The chemical industry's main objective is to create substances that are necessary for society.
- Pharmaceutical: The pharmaceutical industry invests in research to develop new synthesis processes and drugs, including antipyretics, anti-inflammatories, analgesics, and antibiotics.
- Petrochemicals: Synthetic polymers (plastics), synthetic fibers (nylon or polyester), glycerine, and certain solvents.
- Other products: Fertilizers, acids, additives for construction, and food additives, among others.
Environmental Impact of Chemical Reactions
Ozone Layer Depletion
The ozone layer protects the Earth from ultraviolet radiation. Substances such as nitrogen oxides and compounds known as CFCs destroy the O3 (ozone).
Greenhouse Effect
The greenhouse effect is the regulation of the Earth's temperature due to the greenhouse effect layer of gases. The main gases responsible for this effect are carbon dioxide, nitrogen oxide, and methane. Pollution increases the greenhouse effect.
Acid Rain
Acid rain is the phenomenon of rainwater carrying very corrosive acids (nitric and sulfuric acids). These acids form when sulfur oxide (SO2) and nitrogen oxides (NO and NO2) react with water vapor in the atmosphere. Acid rain destroys plants and animals in the environment.