Notes, summaries, assignments, exams, and exercises for Chemistry for Vocational training

Primary and Secondary Production in Ecosystems

Primary production is the increase in biomass per unit of time by producers. This represents the solar energy that plants (autotrophs) store in the chemical bonds of organic compounds through photosynthesis. Conversely, secondary production is the increase in biomass per unit of time by consumers and decomposers.

Gross and Net Primary Production

Gross Primary Production (GPP) is the total amount of energy fixed by producers through photosynthesis. If we discount the energy consumed for the maintenance of vital functions, such as cell respiration (R), we obtain the Net Primary Production (NPP). The net value represents the amount of biomass available to the next trophic level.

The formula is: NPP =

Physical Contamination of Water

Physical contamination involves factors affecting aquatic life, such as suspended solids, turbidity, color, and agents like surfactants (tensoactivos).

Chemical Contamination

Chemical contamination occurs by changing natural chemical factors or introducing foreign substances into the water through industrial effluents. These can include salinity, pH, toxic substances, and marked deoxygenation.

Biotic Pollution

Biotic pollution results from the discharge of biogenic material, which changes the availability of nutrients and the balance of species. As organic matter increases, heterotrophic species also increase, causing changes in food chains and producing organisms that unbalance the ecosystem.

Disadvantages of Impurities

States of Matter

Solid State

Solids are characterized by molecules that are tightly packed with minimal empty spaces. They possess a defined shape and volume and do not flow. Examples include: aluminum, diamond, gold, salt, sugar, flour, and cups.

Liquid State

Liquids consist of molecules with disordered empty spaces, allowing them to flow and adopt the shape of their container. They have a defined volume but no definite shape. Examples include: ethanol, milk, oil, paraffin, water, juice, and cologne.

Gaseous State

Gases have no definite form or volume, adopting the shape and volume of their container. Their molecules are extremely separated and spread rapidly. Examples include: chlorine, nitrogen, Tanax (insecticide), Lucu gas, spray paint, and...

Key Lighting Terminology

Luminous Flux

The amount of light emitted by a light source, measured in lumens (lm).

Luminous Efficacy

The ratio of the luminous flux emitted (in lumens) to the power consumed (in watts). Its unit is lm/W.

Color Rendering Index (CRI)

Indicates the quality level of light sources in reproducing colors as accurately as possible.

Color Temperature (K)

Different light sources emit light at various color temperatures, measured in Kelvin (K). Here are some common examples:

• Incandescent Lamp: 2,800 K
• Fluorescent Lamp (Warm White): 3,000 K
• Fluorescent Tubes (Cool White): 4,000 K
• Fluorescent Tubes (Daylight): 6,000 K
• Direct Sunlight (Clear Sky): 6,000 K

Types of Electric Lamps

Electric lamps are categorized based on their operating principles:...

Historical Discoveries and Early Particle Evidence

Faraday; Stoney (coined the name electron in connection with electricity); cathode-ray tube observations (CRT); Thomson (charge-to-mass ratio of the electron); Millikan (electron charge); Goldstein (canal rays); Aston (mass spectrometer).

Atomic Models and Development

Atomic models—development and key ideas:

• Thomson: plum-pudding model; early ideas from scattering and particulate experiments.
• Rutherford: nuclear atom obtained from alpha-particle scattering; nucleus-centered model. (Reference: neutron discovery by Chadwick.)
• Bohr: combines Rutherford's nuclear atom and Planck's quantum concepts — energy is absorbed or emitted in quanta; discrete postulated orbits; quantized angular momentum

Principal Components of Iron-Carbon Alloys

The main components of iron-carbon alloys include:

• Perlite: Thin films formed with ferrite (light gray) and cementite (dark gray). Carbon content is 0.89%. Ferrite is softer, while cementite is harder.
• Ferrite: Almost pure iron, very soft, ductile, and magnetic. Its structure is cubic.
• Cementite: Located on the right side of the eutectoid point due to its carbon composition (Fe3C). It is the hardest and most fragile constituent of steel.
• Austenite
• Martensite
• Ledeburite: Consisting of cementite and austenite.

Thermal Treatments for Steel

Thermal treatments modify the properties of steel:

• Tempering: Increases hardness, toughness, and yield strength, but also increases fragility. Methods include immersion in water,

Cytology Fixatives

Solution: Cytology fixatives, formerly employing ether/alcohol 96 in equal parts, are now rarely used due to the hazardous nature of ether. The 96% alcohol is most often used. The procedure involves immersing the preparation in the fixative bath for a minimum of 10 to 15 minutes. Other alcohols, such as 100% methanol, 80% propanol, and 80% isopropanol, can also be used. Citospray is used in samples obtained by forced exfoliation.

Sample Types in a Cytology Laboratory

Samples that can reach the lab from samples obtained by:

• Forced exfoliation: Rubbing or scraping with various instruments. This is applied to the skin and organs accessible from the outside.
• Spontaneous exfoliation: Samples containing spontaneously exfoliating

Ionic Compounds and Electrical Conductivity

Why ionic compounds do not conduct electricity in the solid state

Explain why ionic compounds do not conduct electricity in their crystalline form. Electricity can only be conducted when ions are moving. In their crystalline form, the ions in the ionic compound are locked tightly in one place.

When ionic compounds are in a solid, crystalline lattice, cations and anions occupy fixed positions in the lattice. Because electric current in ionic materials is carried by mobile charged particles, the fixed ions cannot move and therefore the solid does not conduct electricity. By contrast, when the lattice is melted or dissolved in a polar solvent such as water, ions become free to move and the substance conducts...

Types of Radiation in Lighting

Termorradiación: This has its origin in the excitation of atoms via thermal means. Electrorradiación: This stems from the excitement resulting from collisions between atoms and ions within an electric field. Fotorradiación: This has its origin in the excitation of atoms by the absorption of radiation whose photons possess their own energy.

Classification of Lamps and Lighting Systems

Incandescent Lamps

Incandescent: Termorradiación that does not need a complex installation; it connects directly to the network and operates by heating a filament. There are three types: 1. Standard, 2. Halogen, and 3. PAR.

Mercury Vapor and Mixed Light

Mercury Vapor: Based on electrorradiación, light is obtained by the electrical...

Understanding Dental Fluorosis

Dental fluorosis is a condition that causes changes in the appearance of tooth enamel. It is caused by overexposure to fluoride in the early years of life when your permanent teeth are developing.

Chemical Formulas

• Nitrous Oxide: N₂O
• Calcium Carbonate: CaCO₃

Cyclic vs. Acyclic Compounds

• Cyclic Compounds: Compounds that have closed rings (e.g., benzene).
• Acyclic Compounds: Compounds that have an open-chained skeleton (e.g., methane).

Antipsychotic Drugs

Antipsychotic drugs are mainly used for treating schizophrenia. However, they can also be used in mania with significant agitation. Example: Haloperidol.

The Four Stages of Anesthesia

1. Stage 1: Analgesia
2. Stage 2: Excitement
3. Stage 3: Surgical anesthesia
4. Stage 4: Medullary paralysis

Sedatives