Essential Chemical Processes and Measurement Devices

Fundamental Chemical Processes

Reduction: Electron Gain in Chemistry

Reduction is an electrochemical process by which an atom or ion gains electrons, implying a decrease in its oxidation state. This process is the opposite of oxidation.

When an ion or atom undergoes reduction:

• It gains electrons.
• It acts as an oxidizing agent.
• It is reduced by a reducing agent.
• Its oxidation state or number decreases.

Hydration: Water Molecule Addition

The term hydration often refers to hydration reactions. This type of reaction involves the addition of one or more water molecules to a particular compound.

Hydrogenation: Adding Hydrogen to Compounds

Hydrogenation is a type of chemical redox reaction resulting in the addition of hydrogen (H₂) to another compound under pressure and in the presence of a catalyst. The usual targets of this reaction are unsaturated organic compounds such as alkenes, alkynes, ketones, nitriles, and amines. Most hydrogenation occurs by direct addition of diatomic hydrogen.

Cracking: Breaking Down Molecules

Cracking is a chemical process by which larger molecules are broken down, thereby producing simpler compounds.

Catalytic cracking, typically performed at 450-500 °C, utilizes catalysts (such as Al₂O₃ or SiO₂, often clay-based) to enhance the fragmentation of heavier components into lighter, more valuable products, complementing the action of heat and pressure.

Fermentation: Anaerobic Oxidation Process

Fermentation is a catabolic process of incomplete oxidation, which is completely anaerobic, with an organic compound as its end product. These end products characterize the different types of fermentations.

Polymerization: Forming Macromolecules

Polymerization is a chemical process by which reactive monomers (low molecular weight compounds) are chemically grouped together, leading to a high molecular weight molecule called a polymer, which can be a linear chain or a three-dimensional macromolecule.

There are many types of polymerization and various systems to categorize them. The main categories include:

1. Addition polymerization and condensation polymerization.
2. Chain-growth polymerization and step-growth polymerization.

Performance Measurement Instruments

Thermometer: Measuring Temperature

A thermometer is an instrument for measuring temperature. Since its invention, it has changed considerably, mainly with the development of digital electronic thermometers.

Early thermometers were often produced based on thermal expansion, preferring materials with a high coefficient of expansion so that, with increasing temperature, the expansion was easily visible. They utilize different temperature scales and units, such as °C (Celsius), °F (Fahrenheit), °R (Rankine), etc. There are also various types of thermometers, including pyrometers, mercury thermometers, gas thermometers, thermocouples, and resistance thermometers.

Pressure Gauge: Fluid Pressure Measurement

A pressure gauge is a measuring device used to measure the pressure of fluids contained in closed containers. There are basically two types: those for liquids and those for gases.

Common types of pressure gauges include:

• Open-tube manometers (often referred to as"truncate" in some contexts, though"open-tub" is more standard).
• Aneroid gauges (also known as"mechanica" gauges).