Gas
Gas is one of the fundamental states of matter, characterized by its lack of a definite shape or volume. Gases can flow freely, expand to fill their containers, and be compressed into smaller spaces. The Earth's atmosphere is primarily composed of gases, with nitrogen and oxygen being the most abundant, comprising nearly 99% of it. Gases play crucial roles in various natural processes, including the greenhouse effect, which helps regulate the planet's temperature, although certain gases can also contribute to pollution and climate change when present in excessive quantities.
Different gases exhibit similar behaviors influenced by factors such as pressure, temperature, and volume. They are generally less dense than liquids or solids and consist of either simple atoms or complex molecules. The study of gases involves understanding gas laws and principles like Dalton's law and the ideal gas law, which govern their behavior under various conditions. Additionally, gases are vital for numerous industrial applications, including the production of metals, lighting, and food preservation. Overall, while many gases are essential for life and various technologies, some can pose environmental and health risks when not properly managed.
Gas
Gas is a state of matter. Gases have no definite shape or volume. They may flow freely and expand to fill a container; they also may be compressed into a smaller container. The atmosphere of Earth is mostly gas. Some gases in the atmosphere are helpful, but others are harmful. Gases serve a number of functions in everyday life.
Overview
Different gases generally behave in similar ways. They are affected by pressure, temperature, and volume, among other variables. Gases are less dense than the same matter in liquid or solid form and will freely combine in the same volume. The particles of a gas may be simple atoms or complex molecules and move freely and rapidly.
Some elements, known as the noble gases, are gases at room temperature. These elements are classified as Group 18 of the periodic table. Helium, neon, argon, krypton, xenon, radon, and ununoctium are noble gases.
Pressure is a measurement of the force per unit area, most commonly measured in pascal. Temperature is a property of matter that pertains to the energy within particles. This property may be measured using several temperature scales, including the Kelvin, Fahrenheit, and Celsius scales. Kelvin, the absolute temperature scale, is used for gas calculations. The standard temperature and pressure(STP) describes the conditions at one atmosphere of pressure at 273 K (equal to 0 degrees C).
Though the chemical properties of gases are different, they all generally obey the gas laws. Gas laws include Dalton's law of partial pressures, Avogadro's law, Boyle's law, Charles's law, Guy-Lussac's law, and the ideal gas law (combined gas law). Chemists also use the kinetic theory of gases, density of a gas, and Graham's law of diffusion and effusion when working with gases.
Gases in the Atmosphere
The atmosphere of Earth is mostly gas. Two of these gases, nitrogen and oxygen, make up about 99 percent of the dry atmosphere. The average composition of the atmosphere contains eleven main gases: nitrogen (78.08 percent), oxygen (20.95 percent), water vapor (0 to 4 percent), argon (0.93 percent), and small percentages of carbon dioxide, neon, helium, methane, hydrogen, nitrous oxide, and ozone.
The amount of water vapor in the air varies considerably. The atmosphere near the equator (over water and rain forests) contains the highest concentration of water vapor, while air over continental deserts and the polar ice caps is frequently very dry, sometimes nearly completely dry. Water vapor is vital in distributing heat on Earth, developing precipitation that provides freshwater, and warming the atmosphere through the greenhouse effect. Greenhouse gases trap heat from the Sun in the atmosphere, preventing it from escaping. As a result, the temperature of Earth rises. An excessive rise in global temperature contributes to glacier melt and other climate-related changes.
Greenhouse Gases
Gases are everywhere. Many, such as oxygen, are beneficial. Other gases may harm us or become pollutants when they collect in larger-than-desired quantities. Many greenhouse gases are pollutants that contribute to global climate change.
Humans and animals emit carbon dioxide when they breathe. Plants use carbon dioxide in photosynthesis and emit oxygen. This balanced cycle enables mammal and plant life to continue. For about 150 years, however, humans have burned large quantities of fossil fuels, which release carbon dioxide into the atmosphere. In the last three centuries, the volume of carbon dioxide has increased by more than 35 percent. Excessive carbon dioxide gas is a pollutant.
Methane and chlorofluorocarbons (CFCs) are other greenhouse gases. Methane is produced in many ways, including rice cultivation, animal grazing, termites, and landfills. The coal, oil, and natural gas industries release methane when they extract deposits of these resources.
Smog is a significant air quality issue. Sulfur dioxide, a toxic gas, is one chemical component of smog. Smog produces the opposite of the greenhouse effect: it prevents sunlight from penetrating the atmosphere, which causes Earth to cool. In the past, most sulfur dioxide in the atmosphere came from volcanic eruptions. Today, it is mostly a human-made pollutant. Although smog is poisonous and dangerous to life, it offers some benefits. Smog offsets some of the warming caused by greenhouse gases.
Ozone, another greenhouse gas, also may be on the rise. However, long-term data is unavailable. Ozone is a component of smog, which is frequently found around and over urban areas.
Uses of Gases
Many gases are necessary for industrial applications. Argon, for example, is used in metallurgy when manufacturing steel and stainless steel and in aluminum smelting. High-tech uses of argon include cleaning silicon chips and producing lasers and fiber optics. Argon is also used in fluorescent tubes and other lightbulbs, and in welding gas mixtures. Acetylene, another gas, is used commonly in welding as well.
Neon is used in lighting tubes and displays and in lasers. Krypton and xenon are also used in lasers. Both have applications in lighting as well: krypton is used in energy-saving bulbs, while xenon is used in lighthouses, some automobile headlights, and flash lighting.
Carbon dioxide is useful in fire suppression systems because it smothers fire by depriving it of needed oxygen. Under pressure, carbon dioxide forms dry ice, a helpful coolant that can transition from a solid state to a gas without becoming a liquid. Dry ice is frequently used in preserving food during transportation and storage. Carbon dioxide is often found in common beverages: this gas gives soda its fizziness.
Hydrogen gas is used in the manufacture of many everyday products. Hydrogenating unsaturated fats and oils thickens them. For this reason, hydrogen is used to create margarine and other food oils and to make many household products, including shampoos and cleansers.
Helium, commonly found in buoyant balloons, also is used in breathing mixtures for divers and those with breathing difficulties and in superconducting magnets. Nitrous oxide, better known as "laughing gas," is used in anesthetics and for light sedation.
Bibliography
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