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

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

XRD for Stress Measurement in Surface Engineering

X-Ray Diffraction (XRD) techniques are employed for stress measurements, particularly in surface engineering. It utilizes Bragg's Law (stated in the source as 2d sin σ, where d is the lattice spacing and σ is related to the diffraction angle; the general form is often 2d sin θ = nλ) and the material's elastic properties to correlate lattice strain with stress values.

Principles and Application

XRD analyzes the diffraction pattern of X-rays interacting with a crystalline material to determine its atomic and molecular structure, including lattice strains which are related to stress.

Advantages of XRD

• Non-destructive
• Fast and simple to perform
• Can be performed in situ (on-site)
• High accuracy for many

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" »

Properties of Matter

Properties of matter help us describe and identify substances.

General Properties

These are properties common to all matter, such as mass and volume. They do not help distinguish one substance from another.

Characteristic or Intensive Properties

These properties are unique to a specific substance and do not depend on the amount of matter present. They are useful for identifying a substance. Examples include density and melting point.

Extensive Properties

These properties depend on the amount of matter present. Examples include mass and volume.

Fundamental Chemical Concepts

Relative Atomic Mass

The relative atomic mass of a chemical element is the ratio of the average mass of atoms of an element to one twelfth of the mass of an atom... Continue reading "Foundations of Chemical Principles" »

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