Chemical Reactions, Conservation Laws, and Consumer Price Index (CPI)

Fundamental Concepts of Chemical Change

Phenomenon

Any change that takes place within material systems.

Physical Change

Events in which there is no change in the composition or identity of the substances involved.

Chemical Change

Events in which the identity of the substances involved is altered.

Chemistry (Chemical Transformation)

The transformation of one substance into another. This process involves breaking existing chemical bonds and forming new ones.

Final Substance (Reaction Products)

The substances resulting from a chemical reaction.

Chemical Reaction Dynamics

Reversible Reactions

Chemical equations where the conversion of reactants to products occurs simultaneously with the conversion of products back to reactants (equilibrium).

Irreversible Reactions

Reactions that proceed in only one direction, from reactants toward products.

Exothermic Reactions

Reactions that occur spontaneously and are accompanied by a release of energy (heat).

Endothermic Reactions

Reactions that require and absorb energy to occur.

Fundamental Laws of Chemistry

Law of Conservation of Mass (Lavoisier's Law)

The total mass of the substances involved in a chemical reaction remains constant and unchanging.

Law of Constant Proportion (Proust's Law)

When two substances combine to form a compound, they always do so in a constant weight ratio.

Classification of Chemical Reactions

Synthesis Reactions

Reactions in which two or more simple substances combine to form a more complex compound (e.g., A + B → AB).

Most Common Synthesis Types:

• Oxidation
• Combustion

Redox Reactions (Reduction-Oxidation)

A reaction in which both oxidation and reduction occur simultaneously.

Oxidation

Any process in which an element or compound gains oxygen. Example: 2F₂ (g) + O₂ (g) → 2F₂O (g)

Reduction

Any process in which an element or compound loses oxygen. Example: CuO + H₂ → Cu + H₂O

Combustion Reactions

A rapid oxidation reaction that releases light and thermal energy (heat).

Ignition Point

The minimum temperature a fuel must reach for combustion to begin.

Incineration

The process by which materials are destroyed by controlled combustion.

Decomposition Reactions

Reactions where a single compound splits to form two or more simpler substances. These reactions typically require an input of energy to proceed.

Consumer Finance and Economic Indicators

Utility Billing Components

Electricity Bill (Monthly)

• Billing Period: 1 month
• Contracted Power
• Electricity Consumption
• Excise Duty on Electricity
• Other charges (e.g., equipment rental, service fees)

Water Bill (Quarterly)

• Billing Period: 3 months
• Fixed charges
• Variable charges (which may vary by region)

Value Added Tax (VAT)

A consumption tax applied to the value added to an article at each stage of production or distribution.

Claim

A formal complaint filed with providers, administrative bodies, or a judge. Claims may be oral or written.

Saving

The practice of prioritizing essential needs and setting aside resources.

Consumer Price Index (CPI)

An economic indicator used to map the evolution of prices for a basket of goods and services commonly consumed by households.

CPI Calculation

Calculated by comparing the prices of a fixed set of products acquired by consumers over a specific period, measuring the price variation of each item.

Base Price

The starting point (time period) from which price variations are measured for the CPI calculation.