Notes, summaries, assignments, exams, and problems for Chemistry

Mole of atom - is the amount of a chemical element equivalent to the atomic mass expressed in grams

Mol substance - ekivalent the quantity k represents the molecular mass expressed in grams (6,022 · 10_23 atomic number)

Molar mass - mass is the substance in 1 mol

Solutions - homogeneous mixture of two or more substances (solute-solvent +)

Molarity - is the way to express the concentration of M = moles solute / volume of solution (l)

Speed of reaction - temperature, concentration, degree of division, nature of reagents, catalysts presence, media pH

theory of collisions - zoquen reactive particles together and break the links that hold together their atoms and are joined forming substances in November

Reagent used for the chemical reaction

... Continue reading "Coh3 chemical name" »

Chemical Reactions and Fundamental Principles

A chemical reaction is any process in which substances, known as reactants, transform into different substances called products. According to the Law of Conservation of Mass (Lavoisier's Law), the total mass must remain constant throughout the process.

Chemical Equations and Stoichiometry

A chemical equation is a symbolic representation of a reaction. If the number of atoms for each element is not equal on both sides, a stoichiometric coefficient must be added to balance the equation.

The performance (yield) of an equation is usually expressed as a percentage, representing the ratio of the amount of product actually obtained compared to the amount obtained theoretically.

Fundamental Laws of Chemistry

• Law

Basic and Acidic Oxides

METAL + O₂ → a basic oxide. A basic oxide + H₂O → a hydroxide. An oxide can react to form a salt and H₂O.

METAL + H₂O → typically forms a hydroxide (in some cases, hydrides may form).

NONMETAL + O₂ → an acidic oxide (acid anhydride). An acidic oxide + H₂O → an acid; acids can form salts + H₂O in neutralization reactions.

Basic oxides: definition and examples

Basic oxides: These are binary compounds formed by the union of a metal with oxygen.

Basic oxide formation examples: METAL + O₂ → a basic oxide. Examples:

• Na + O₂ → Na₂O
• Ca + O₂ → CaO
• Al + O₂ → Al₂O₃

Formation of hydroxides from oxides

The oxides combine with H₂O to form hydroxides:

• Na₂O + H₂O → 2 NaOH
• CaO + H₂O → Ca(OH)₂
• Al₂O₃ + H₂O → 2 Al(OH)₃ (depending

States of Matter

• Solid State: Attractive forces are greater than repulsive forces. They possess a defined shape and volume, are rigid, and cannot be compressed. Molecules are highly ordered.
• Liquid State: These do not have a proper form but maintain a specific volume, adapting to the shape of the container. Molecules are disordered, and forces of attraction and repulsion are balanced.
• Gaseous State: These have no defined form or volume, conforming to the shape of the container. Molecules are separated by repulsive forces and can be compressed easily. Component molecules move freely.

Changes in State

• Solid to Liquid: Fusion
• Liquid to Solid: Solidification
• Liquid to Gas: Vaporization
• Gas to Liquid: Liquefaction or Condensation
• Gas to Solid: Sublimation
• Solid

Fundamental Types of Chemical Bonds

The Ionic Bond

The ionic bond results from the electrostatic attractive force between ions of opposite charge, i.e., between a strongly electropositive atom and a highly electronegative atom. This bond usually occurs between a metal and a non-metal.

There is a total electronic transfer from one atom to another, forming ions of opposite charge:

• The metal provides one or more electrons to form positively charged ions, or cations, achieving a stable electronic configuration.
• These electrons then enter the non-metal, forming a negatively charged ion, or anion, which also achieves a stable electron configuration.

The electrostatic attraction between these oppositely charged ions causes them to unite and form an ionic... Continue reading "Chemical Bonds Defined: Ionic, Covalent, and Metallic Structures" »

Physical Properties of Water

The boiling and melting points of water are abnormally high relative to other hydrides in its chemical family. This is primarily due to the existence of hydrogen bonds.

Density Behavior

• From 0°C to 4°C, the density of water increases.
• From 5°C to 100°C, the density decreases.

Heat Capacity and Latent Heats

Water exhibits high values for both heat capacity and latent heats of melting and vaporization.

Definitions:

• Specific Heat Capacity (C_c): The amount of heat required to increase the temperature of a unit mass of a substance.
• Latent Heat (C_l): The heat required to change the state of a substance without increasing its temperature.

Key Values:

• Heat of Vaporization: 539.5 cal/g
• Heat of Fusion: 79.7 cal/g

Climate Regulation

Steel Alloys and Carbon Content

Steel is an alloy of iron and carbon. Carbon steels are classified by their carbon content:

• Low Carbon Steels: 0.06% to 0.25% carbon (soft or sweet steels).
• Medium Carbon Steels: 0.25% to 0.50% carbon (semi-hard or semi-soft steels).
• High Carbon Steels: 0.50% to 1.67% carbon (hard or extra-hard steels).

Alloy Steels

Alloy steels contain less than 1% carbon and include additional chemical elements. Types include:

• Cobalt, chromium, sulfur, molybdenum, lead, silicon, vanadium, and tungsten steels.

Stainless Steel

Stainless steel offers high hardness and resistance to oxidation and wear. It is classified by its nickel and chromium content:

• Ferritic Stainless Steel: Contains between 10% and 18% chromium.
• Martensitic and Austenitic

Atomic and Molecular Weights

O₂ 1:7.93

The relationship between oxygen and hydrogen is 1:7.93. Dalton stated that the atomic weight of oxygen (with valence 2) was 7.92; the modern relative atomic mass of oxygen is about 16.

Avogadro's Principle and Molar Number

Avogadro

Avogadro's principle states that equal volumes of different gases, at the same temperature and pressure, contain the same number of molecules. This allows comparison of molecular weights: the relative density of one gas to another reflects the ratio of their molecular weights.

In a gas, there are approximately 6.023 × 10²³ molecules per mole (Avogadro's number).

Equivalent Weights and Valence

Equivalent weight of a compound is the molecular weight divided by its valence (the combining... Continue reading "Atomic and Molecular Weights, Subatomic Particles and Solutions" »

Drinking Water Purification

Raw Water Treatment

1. Screening: Raw water passes through gratings, filters, and screens to remove coarse solids.
2. Aeration: Oxidation of undesirable organic species improves taste and odor.
3. Coagulation: Colloidal particles are coagulated and flocculated.
4. Sedimentation: Solids are allowed to settle and are removed.
5. Filtration: Removal of any remaining coagulated solids.
6. Disinfection: Control of bacteria.
7. Softening: Using lime and soda methods.
8. Demineralization: By distillation or ion exchange resins.

Wastewater Treatment

Primary Treatment

1. Screening/Roughing: Removal of large objects and solids through sieves.
2. Grit Removal
3. Skimming
4. Sedimentation: Takes place in tanks or chambers where suspended solids settle. This removes approximately

Arrhenius Theory of Acids and Bases

According to the Arrhenius theory, acids and bases exist only in aqueous solution:

• Acid: Any substance that in aqueous solution dissociates with the formation of hydrogen ions, H⁺.
• Base: Any substance that in aqueous solution dissociates with the formation of hydroxyl ions, OH^-.

Neutralization Reaction

Neutralization is the complete reaction of an acid and a base with the formation of a salt and water. HA + BOH → AB + H₂O.

Brønsted-Lowry Theory

According to the Brønsted-Lowry theory, the concepts of acid and base were expanded:

• Acid: Any chemical species, molecular or ionic, capable of yielding an H⁺ ion to another substance.
• Base: Any chemical species, molecule or ion, capable of receiving an H⁺ ion from another