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

Physical Properties of Alcohols

• State: Lower alcohols are liquids; higher alcohols are solids.
• Density: Less dense than water.
• Boiling Points: Higher than corresponding alkanes.
• Solubility: Decreases as the number of carbon atoms increases.

Common Alcohols

• Methanol: CH₃OH
• Ethanol: CH₃CH₂OH

Ethanol Production

• Natural: C₆H₁₂O₆ → 2CH₃CH₂OH + 2CO₂
• Artificial: CH₂=CH₂ + H₂O → CH₃CH₂OH

Chemical Properties of Alcohols

Alcohols undergo oxidation reactions that distinguish primary, secondary, and tertiary structures:

• Primary Alcohols: Oxidize to form aldehydes (e.g., CH₃CH₂OH + ½O₂ → CH₃CHO + H₂O).
• Secondary Alcohols: Oxidize to form ketones (e.g., CH₃-CHOH-CH₃ + O₂ → CH₃-CO-CH₃ + H₂O).
• Tertiary Alcohols:

Topical Excipients

1. Vehicles

• Hydrophobic: Silicones (bentonite, dimethicone), alcohols, hydrocarbons (liquid paraffin, petrolatum), sterols (lanolin), and carboxylic acid esters.
• Cosolvents: Polyols (propylene glycol, glycerin, sorbitol) and esters (polyethylene or polypropylene).

2. Functional Agents

• Emulsifiers: W/O (esters, phenols, mono- or polyesters); O/W (lauryl sulfate, polyoxyethylene sorbitan).
• Preservatives: Phenols (to inhibit microorganism growth).
• Viscosity Agents
• pH Regulators
• Moisturizers
• Antioxidants: BHA, BHT, ascorbic acid.

3. Powder Processing

1. Identify heavy constituents.
2. Sift each component.
3. Mix in a mortar (verify weight) or industrial V-mixer.
4. Sift the final mixture (verify weight).
5. Dosing and distribution: Volumetric dosing.
6. Packaging:

Electric Nature of Matter

Matter undergoes electric phenomena. It can be uncharged (neutral), positively charged, or negatively charged.

• Like charges repel, and opposite charges attract.
• A body is neutral when it has an equal number of positive and negative charges.
• A positively charged body has more positive charges than negative charges.
• A negatively charged body has more negative charges than positive charges.

Electric charge in various media, and the forces exerted between charges, are described by Coulomb's Law.

Coulomb's Law

The force (F) between two point charges (Q₁ and Q₂) is directly proportional to the product of the charges and inversely proportional to the square of the distance (D) between them.

F = k * (Q₁ * Q₂) / D²

Where:

• Q: Electric

Atomic Models

Dalton's Atomic Model

Dalton proposed that atoms are indivisible, compact spheres with specific weights, explaining chemical reactions. However, this model doesn't explain the electrical nature of matter.

Rutherford's Atomic Model

Rutherford's experiment involved firing positively charged alpha particles at a gold foil. Most particles passed through undeflected, some were diverted, and others bounced back, leading to a new understanding of atomic structure.

Chemical Bonds

Ionic Bonds

When a metal is in the presence of a non-metal, a transfer of electrons occurs, forming ions with opposite charges. These ions are held together by electrostatic attraction. The ionic bond forms between ions of opposite charges. Ionic valence refers to... Continue reading "Atomic Models, Chemical Bonds, and Scientific Method" »

Links and interaction:
Link: q down at junctions to form dif compounds and the goal is stability.

E. Ionian (+ strong) (M + NM)
The - in Cedeno E. And the + to reach. Both can be combined.
E. Covalent (+ weak) (NM + NM) (EX: cl2, CO2, H2, H20)
I share their valence.
E. Metallic. + ions form networks, move easily, the latest E levels (valence).
Intermolecular forces: it depends on physical condition and character of st ud them. The + weak Van der Waals.
Ranking 2: dipoles (between E. Covalent polar mol), polarization transient (london: between nonpolar covalent mol), PH (an H is linked to another major in such as O, N or F) <P Boiling affects ..
Mixing:
Solubility of a solute: q max amount is dissolved in a fixed amount of a solvent... Continue reading "Chemical Principles: Bonds, Solutions, and Gas Laws" »

Understanding Carbohydrates

Carbohydrates are biomolecules primarily composed of carbon, hydrogen, and oxygen. Their atoms are linked to alcohol groups (hydroxyl groups, -OH) and hydrogen atoms (-H). All carbohydrates contain a carbonyl group (C=O), which can be either an aldehyde group (-CHO) or a ketone group (-CO). Therefore, they can be defined as polyhydroxyaldehydes or polyhydroxyketones.

Classification of Carbohydrates

Carbohydrates are classified into several groups:

• Monosaccharides: Simple sugars made of single units.
• Oligosaccharides: Contain between 2 and 10 monosaccharide units.
• Polysaccharides: Formed by multiple repeating units of monosaccharides, further divided into:
  • Homopolysaccharides: Formed by the repetition of a single monomer.

Analysis and Instrumentation

Physical Properties:

• Hardness
• Color
• Shape
• Smell
• Ductility
• Density
• Flavor
• Malleability
• Volatility
• Viscosity
• Conductivity
• Weight
• Volume
• Brightness
• Porosity
• Toughness
• Boiling Point (Punto de ebullición)
• Melting Point (Punto de fusión)

Chemical Properties:

Chemical reactions.

Composition:

CaCO3 100%

Determining the Composition of Liquids, Gases, and Solutions: Instrumental Applications

Objectives:

• To know the fundamentals and applications of instrumental techniques in environmental engineering.
• Understand the general problem of analysis.
• Purchase criteria for a particular control method.
• Analysis, sampling, preservation, and preparation of samples.
• Distinguish the key parts and functions of each instrumental technique.
• Interpret information obtained

Chemical Bonds and Properties

Ionic Bonds

Ionic bonds are characteristic of compounds formed between a metal and a non-metal. Metals form positive ions (cations), and non-metals form ion-accepting negative ions (anions).

Properties of Ionic Compounds

• Soluble in water
• Hard and fragile
• Have an ionic crystal structure

Covalent Bonds

Covalent bonds are seen in particles formed by atoms of non-metals, as is the case of diatomic gas molecules. Atoms share one or more pairs of electrons to complete their outer octet.

Properties of Covalent Compounds

• Do not conduct electric current
• Molecules of simple gases have covalent bonds
• Have atomic or molecular crystalline structure

Types of Covalent Bonds

• Polar Covalent
• Non-Polar Covalent
• Coordinate Covalent: Two electrons

Lipids: Classification and Key Characteristics

LIPIDS: Lipids are classified into three major groups: fatty acids (saturated and unsaturated), saponifiable lipids (simple and complex, including acylglycerides and waxes) and unsaponifiable lipids (terpenes, steroids and prostaglandins).

Fatty Acids: Structure and Properties

Fatty acid: a hydrocarbon chain typically from 12 to 22 carbon atoms with a terminal COOH (carboxyl) group. They are divided into:

• Saturated fatty acids — chains with no double bonds; they adopt an extended, zigzag conformation and have stronger van der Waals interactions between hydrocarbon chains, producing higher melting points.
• Unsaturated fatty acids — chains that contain one or more double bonds; double bonds create

Atomic Structure and Chemistry Fundamentals

Organic chemistry is the science of matter. All matter occupies space. Plasma is when atoms are in a high-temperature environment.

• Elements: A single type of atom that cannot be transformed into simpler substances.
• Compounds: Substances formed by different types of atoms combined in a constant ratio.
• Homogeneous: Has a single phase, and components are indistinguishable (H₂O + C₆H₁₂O₆). Can be separated by evaporation or distillation.
• Heterogeneous: Components can be distinguished from each other.
• Phase: A portion of matter with definite limits. Can be separated by filtering or decanting.

d = mass / volume

Prefixes: milli (m) - 10^-3 / micro (μ) - 10^-6 / nano (n) - 10^-9

1 kg = 1000 g and 1 dozen = 12 units

Temperature... Continue reading "Atomic Structure, Compounds, and Chemical Formulas" »