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

Substances, Mixtures, and Separation Techniques

1. Pure Substances vs. Mixtures

• Distilled Water: Pure substance/compound
• Tap Water: Mixture/homogeneous
• Diamond: Pure substance/element
• Gasoline: Mixture/homogeneous
• Wine: Mixture/homogeneous
• Air: Mixture/homogeneous

2. Dalton's Theory

• Matter is made up of indivisible and indestructible atoms.
• All atoms of the same element are equal in mass and properties.
• Compounds are formed by the combination of different elements.

3. Separation Techniques

• Screening: Separates solid particles of different sizes. Instrument: sieve.
• Filtration: Separates solids from liquids. Instrument: filter.
• Evaporation: Separates solids from liquids when the liquid is not needed. Works best with homogeneous mixtures. The process is faster

Aluminum

Aluminum is used in telescopes. Tempered powder paint is used in metal protection and the preparation of alloys. Aluminum forms alloys with other metals. Duralumin, an aluminum alloy, is used in aeronautics because it is very lightweight and has great resistance.

Aluminothermy

Aluminothermy is a metal extraction procedure that reduces metal oxides using aluminum powder. Metals such as chromium, manganese, and molybdenum are obtained using this method.

Salts of Aluminum

Important industrial salts are called alum (double salts).

Natural Aluminum

Aluminum is not found free in the Earth's crust. It is named after these characteristics:

1. Alumina
2. Hydroxide
3. Silicates

Obtaining Aluminum

Aluminum is extracted using the electrolytic method. Bauxite and cryolite... Continue reading "Aluminum, Copper, Polymers, and Ceramics: Properties and Uses" »

Fuel Properties and Combustion

Oil is formed by the decomposition of organic matter, primarily plankton, in marine environments. It contains the remains of animals and is a mineral found in sedimentary rock formations.

Soluble compounds begin to form, undergoing thermal decomposition into hydrocarbons (HC).

Gaseous Fuels

Gaseous fuels, also called hydrocarbons (HC), are designed for use in combustion. They are divided into natural gas fuels and manufactured gaseous fuels.

Advantages and Properties of Gaseous Fuels

The calorific value varies greatly depending on the type of gas and the presence of non-combustible components. Non-combustible components lower the heat efficiency of combustion.

Calorific value is the heat released during combustion.

Specific

Review Waxing Techniques

Cusp Placement: Marginal Ridge Occlusion (Upper Jaw)

This section details the placement of cusps in the upper jaw to achieve a marginal ridge top occlusion.

1. First premolar: Distal fossa of the first premolar.
2. Second premolar: Distal fossa of the second premolar.
3. First molar: Mesio-lingual cusp, central fossa of first molar.
4. First molar: Disto-lingual cusp, distal marginal ridge of the first molar and mesial marginal ridge of the second molar.
5. Second molar: Mesio-lingual cusp, central fossa of the second molar.
6. Second molar: Disto-lingual cusp, distal marginal ridge of the second molar.

Cusp Placement: Cusp to Fossa Occlusion (Upper Jaw)

This section describes cusp placement in the upper jaw for a cusp to fossa occlusion.

1. First

Mineralogy

Mineralogy is the science that studies the physical and chemical properties of minerals.

Mineral Classifications

Primary Minerals

Primary minerals are minerals found in their original deposits. An example is pyrite (FeS₂), known for its gold-like color and luster.

Secondary Minerals

Secondary minerals form from chemical reactions involving primary minerals. Anglesite (PbSO₄) is a secondary mineral derived from the primary mineral galena (PbS).

Solid Structures

Crystalline Solids

Crystalline solids have particles arranged in an orderly and regular pattern in three dimensions, following a defined geometric structure.

Amorphous Solids

Amorphous solids have particles arranged randomly, similar to the structure of liquids, resulting in a shapeless... Continue reading "Introduction to Mineralogy and Mineral Properties" »

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" »

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" »

Matter: Core Properties, States, and Mixtures

Matter is anything that has mass and occupies volume. It is characterized by two types of properties:

Key Properties of Matter

• General properties: These are mass and volume.
• Specific properties: These are different in each material, so they serve to differentiate materials from each other and assign them different uses.

The Three States of Matter

Matter can occur in three states:

• Gas: A gas has no definite shape and spreads to fill its container. It can be compressed and expands greatly with temperature.
• Liquid: A liquid does not hold its own shape (it takes the shape of its container) but has a definite volume. It is not easily compressed and expands slightly with increasing temperature, although much

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" »