Notes, abstracts, papers, exams and problems of Chemistry

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.

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" »

Osmosis, Buffers, Colloids, and Carbohydrates

Osmosis: Osmosis occurs when two solutions with different ionic concentrations are separated by a semipermeable membrane that allows water to pass through but restricts the passage of ions. There are three types of solutions: isotonic, hypertonic, and hypotonic.

Buffer Systems

In organisms, buffer systems are crucial for maintaining a stable pH in fluids. These systems prevent abrupt pH changes. Buffers are based on the properties of weak acids, which do not dissociate completely. Within a specific pH range, they act as proton donors and acceptors, maintaining a constant pH within certain limits. Certain salts and corresponding acids balance the pH. For example, the HCO-3/H2CO3 (bicarbonate buffer)... Continue reading "Osmosis, Buffers, Colloids, and Carbohydrates: A Concise Review" »

Photosynthesis: Anabolic Process Converting Inorganic to Organic

Photosynthesis converts inorganic matter into organic using solar light. Sunlight's energy is converted into chemical energy within organic compounds. During photosynthesis, oxygen (O2) is released into the atmosphere. The overall process can be summarized as: CO2 + H2O + Light -> Organic Matter + O2.

However, this simplified equation doesn't reflect the actual process. The oxygen released comes from water, not carbon dioxide. Glucose formation and oxygen release are independent processes.

Light Phase (Hill Reaction)

The light phase occurs in the thylakoids, where photosystems are located. It requires light and produces:

• Reducing power: NADPH + H+
• Energy: ATP (produced using sunlight)

Understanding Material Systems and Separation Techniques

Heterogeneous system material should appear uniform. Akella system material is presented uniformly. All points of the material system are separated for experimental study.

Decompose a compound using chemical procedures into simple substances. A simple substance is a pure substance that cannot be decomposed into other simpler substances by ordinary chemical procedures. A simple substance is formed by a single type of element. A compound is a pure substance formed by two elements combined in fixed, homogeneous proportions.

Dissolving creates a blend made uniform by two pure substances in variable proportions.

Simple Distillation

Used to separate a dissolving liquid formed by two points with... Continue reading "Understanding Heterogeneous and Homogeneous Systems" »

Metals: Properties, Processing, and Applications

Copper

Classification: Density > 5. Danger 5-2, Ultralight < 2.

Advantages: Electrical and thermal conductivity, oxidation and corrosion resistance, low melting point.

Disadvantages: Lower mechanical resistance, more difficult and expensive to obtain.

Sources:

• Native copper: (Poor mineral, not usually found)
• Sulfides: Chalcopyrite and chalcocite
• Oxides: Malachite and cuprite

Characteristics: Reddish, relatively soft, high electrical conductivity, very ductile and malleable, moderate resistance to acids.

Obtaining Process:

• Wet process: Copper < 10%. Diluted sulfuric acid is added to an electrolytic bath.
• Dry process: Copper > 10%. Crushing, grinding, mineral separation, and gangue by flotation

Le Chatelier's Principle

Changes in Concentration

When a quantity of a substance is added to an equilibrium system, it will move to the side where the substance is not present. If, however, we remove one of the substances, the equilibrium shifts to the side where it is located.

Changes in Pressure Affecting Volume

When the pressure is increased from the outside and the system decreases in volume, the equilibrium shifts in the direction where there is a smaller number of moles (or molecules) to counteract the external perturbation.

Changes in Temperature

An increase in temperature always favors the endothermic process, and a decrease favors the exothermic process. If the direct process is endothermic, a temperature increase leads to a higher value... Continue reading "Le Chatelier's Principle and Carbon Chemistry Properties" »

Proton: Positive electricity - 1.602 x 10^-19 electric charge and its mass is greater than 27 kg. 1.672 x 10^-27 kg. Electron: Electric negative charge (mass is approximately 0.000548 Daltons). Neutron: Neutral charge (mass is almost equal to that of the proton, 1.675 x 10^-27 kg).

Concept of Mole: A practical means to handle the large number of particles involved in a chemical reaction. If two quantities have the same number of atoms or molecules, their masses are in the same proportion as their respective atomic or molecular masses. The mole is the unit of the number of particles contained in an amount of substance equal to its molar mass. This number is called Avogadro's number (the number of atoms in 12 grams of Carbon-12). Atomic mass is expressed... Continue reading "Understanding Protons, Electrons, and Chemical Bonds" »

What is an Inorganic Compound?

Inorganic compounds are substances formed by various chemical elements. Unlike organic compounds, the main component in inorganic compounds is not always carbon. Water is the most abundant inorganic compound. Almost all known elements can be involved in the formation of inorganic compounds.

History of Inorganic Chemistry

• The beginnings of inorganic chemistry trace back to the history of civilized man. Since the early metal ages, people have been devoted to understanding the minerals in deposits and how they react under certain conditions.
• Later, during the Middle Ages and Renaissance, significant knowledge was gained through the pursuit of a reaction that could lead to gold from other metals. This practice was known

Chemical Bonding

Chemical bonding is the attractive force that holds atoms together in atomic groupings. Atoms that achieve stability by sharing electrons with other atoms are linked by a covalent bond.

Water

Water remains liquid at room temperature, whereas other similar substances are immediately converted into gases.

• The density of water increases to abnormally high temperatures from 0 to 4°C, reaching a maximum value of 1000 kg/m³. Above or below these temperatures, water expands, and its density decreases.
• In its solid state, water floats on liquid water, contrary to what occurs with other substances.
• Water is an excellent heat storage medium. Its resistance to increasing or decreasing its temperature is higher than that of other liquids or