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

Furnace Operations and Combustion Principles

Gas burners and fuel oil burners are the two primary types of furnace burners. Furnaces usually operate with 0.5 - 2.0% excess oxygen to maintain efficiency. During the process, furnace fuel and incomplete combustion form carbon dioxide and water.

Safety and Air Supply in Furnaces

Flame monitors ensure that a flame is lit in the burner at all times when the fuel safety shutoff valves are open. Balanced draft furnaces are the type of furnaces that use two fans: one inducing flow out of the stack and the other feeding air to the burners. To ensure complete combustion, secondary air is supplied to the furnace.

Extraction and Mass Transfer Processes

When the extract mixture has reached a point at which it... Continue reading "Industrial Furnace, Extraction, and Reactor Operations" »

Heat vs. Enthalpy

Enthalpy is a property of a system, sometimes termed "heat content." It represents the system's internal energy (U) plus the product of pressure and volume (pV).

Heat is energy in transit, transferred between systems. Enthalpy (H) is a state function defining the system's state.

Hess's Law and Enthalpy

Hess's law states that the total enthalpy change for a multi-step reaction equals the sum of enthalpy changes for each individual step. This principle, grounded in the conservation of energy, allows for calculating ΔH even when direct measurement is impossible. It enables the determination of standard enthalpies of formation, useful for designing complex syntheses.

Enthalpy and Reaction Types

Enthalpy determines whether a reaction... Continue reading "Heat vs. Enthalpy, Hess's Law, Reaction Types, and Chemical Properties" »

^{Correction fluid is a white liquid. The organic solvent was originally used as an ingredient in the product. This solvent is readily absorbed by the lungs via inhalation. It has been replaced by a safer alternative for painting over mistakes. A brush (which was later replaced by a foam applicator) is attached to the cap, so when the bottle is closed, the brush is immersed in the fluid. When unscrewed, the brush is covered in liquid which is then painted over the mistake. However, it is still possible to see that the product has been used, and also the original content if the paper is held up to a light.}

Functions of Language

• Expresiva or emotiva: expresses feelings
• Funcion apelativa: incites the receiver
• Representativa: provides information
• Poetica

Chemical Energy and Molecular Bonds

Chemical energy is the energy associated with chemical bonds and intermolecular attraction. The chemical energy of a set of reacting substances changes since bonds break and form new bonds, creating new products.

We call the energy exchanged in the form of heat between a system containing a chemical reaction and its surroundings the heat of reaction.

Exothermic and Endothermic Reactions

• Exothermic Reaction: The energy of the reactants is greater than that of the products and has a negative sign (e.g., combustion). These reactions release chemical energy via heat.
• Endothermic Reaction: The energy in the system grows. The exchange of energy via heat goes from the surroundings toward the system, so the heat of reaction

•Animals, plants, fungi, and most protists depend on mitochondria for energy to grow and survive

•There are more than 100 known mitochondrial disorders (including Luft syndrome)

•Defective mitochondria also contribute to many age-related problems (including Alzheimer’s)

•Aerobic respiration

•Form of cellular respiration in eukaryotes and many prokaryotes

•Oxygen is a reactant in the ATP producing process

•Anaerobic respiration

•Form of cellular respiration in some prokaryotes

•A molecule other than oxygen, such as sulfate or nitrate, is used in the ATP-producing process

•Photosynthesis stores energy from sunlight in electron-rich fuel molecules (such as sugars)

•Cellular respiration moves electrons from fuel to other molecules... Continue reading "Mitochondria, Respiration, and Photosynthesis: Energy Processes in Cells" »

ACID OR BASES: Substances that react with each other according to the following reaction

Nomenclature

Nomenclature: Binary ionic compounds involves combining the names of the compound’s positive and negative ions. The name of the cation is given first, followed by the name of the anion.
Binary compounds: Compounds composed of two elements.

Systems

Stock: uses a Roman numeral to indicate an Ion's charge.

Systematic: naming molecular compounds based on the use of prefixes.

Traditional: the latin names of chemical elements.

Types of Inorganics

Binary Ions: monatomic+monatomic

Ternary Ions: monatomic + polyatomic

Binary Acids: H + monatomic ( Hydro- & -ic acid )

Ternary Oxyacid: H +polyatomic ( -ate, -ide → -ic acid) ( -ite → -ous acid)

The Mole Concept

The mole concept is an International System unit of measurement for a substance. It is also represented by carbon-12, and 1 mole is equal to Avogadro's number (6.022 x 10^23).

The Periodic Table's Role in Stoichiometric Calculations

We use the periodic table to get values for given elements in a reaction to obtain their atomic values. We can then use these values for conversion from grams to moles or moles to grams in stoichiometric-based problems (gram/mole, mole-gram conversions).

Heat vs. Enthalpy

Heat is the energy that flows between a system and its surroundings due to a difference in temperature.

Enthalpy is equivalent to the total heat content of a system.

Why Only Enthalpy Explains Energy Associated with Chemical Bonds

Because... Continue reading "Principles of Chemistry: From Stoichiometry to Molecular Orbital Theory" »

Definition of Average Speed

The average speed of a body is the total distance traveled divided by the total time taken to cover this distance.

Electron Shells in Sodium Ion (Na+)

Na+ is a positively charged sodium ion. Normally, an atom of sodium has 11 electrons; according to the formula, it has 2 electrons in the K shell, 8 electrons in the L shell, and 1 electron in the M shell. However, Na+ has only 10 electrons; therefore, it has 2 electrons in the K shell and 8 in the L shell. Since 2 and 8 are the full capacities of the K and L shells respectively, Na+ has completely filled K and L shells.

Safety Measures in High Jump Events

In a high jump athletic event, athletes are made to fall on either a cushioned bed or a sand bed. If the athlete were... Continue reading "Essential Science Concepts and Physics Calculations" »