Category Chemistry

WHAT IS SMELTING?

Smelting is what is known as a reduction reaction. It is a method of extracting iron from iron ore. Iron ore, or haematite, is a rock that contains iron and oxygen. The process of smelting takes place in a blast furnace, where iron ore, limestone and coke (a form of carbon) are heated together while hot air is blasted into the furnace. The carbon in the coke reacts with the oxygen in the air to form carbon monoxide. This is turn takes oxygen from the iron ore, leaving behind iron mixed with a little carbon.

The majority of Earth’s iron, however, exists in iron ore. Mined right out of the ground, raw ore is mix of ore proper and loose earth called gangue. The ore proper can usually be separated by crushing the raw ore and simply washing away the lighter soil. Breaking down the ore proper is more difficult, however, as it is a chemical compound of carbonates, hydrates, oxides, silicates, sulfides and various impurities.

To get to the bits of iron in the ore, you have to smelt it out. Smelting involves heating up ore until the metal becomes spongy and the chemical compounds in the ore begin to break down. Most important, it releases oxygen from the iron ore, which makes up a high percentage of common iron ores.

The most primitive facility used to smelt iron is a bloomery. There, a blacksmith burns charcoal with iron ore and a good supply of oxygen (provided by a bellows or blower). Charcoal is essentially pure carbon. The carbon combines with oxygen to create carbon dioxide and carbon monoxide (releasing lots of heat in the process). Carbon and carbon monoxide combine with the oxygen in the iron ore and carry it away, leaving iron metal.

In a bloomery, the fire doesn’t get hot enough to melt the iron completely. Instead, the iron heats up into a spongy mass containing iron and silicates from the ore. Heating and hammering this mass (called the bloom) forces impurities out and mixes the glassy silicates into the iron metal to create wrought iron. Wrought iron is hardy and easy to work, making it perfect for creating tools.

Tool and weapon makers learned to smelt copper long before iron became the dominant metal. Archeological evidence suggests that blacksmiths in the Middle East were smelting iron as early as 2500 B.C., though it would be more than a thousand years before iron became the dominant metal in the region.

­To create higher qualities of iron, blacksmiths would require better furnaces. The technology gradually developed over the centuries. By the mid-1300s, taller furnaces and manually operated bellows allowed European furnaces to burn hot enough to not just soften iron, but actually melt it.

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WHY IS IRON AN IMPORTANT METAL?

Iron is the most widely used of all metals. It is cheap and very strong, so it can be used to make the supports for huge buildings and bridges. The Industrial Revolution would not have been possible without iron to make the machinery used in new factories. Today most iron is made into steel, a metal that can be used for a wider variety of purposes than any other metal on Earth.

Iron is an incredibly useful substance. It’s less brittle than stone yet, compared to wood or copper, extremely strong. If properly heated, iron is also relatively easy to shape into various forms, as well as refine, using simple tools. And speaking of those tools, unlike wood, iron can handle high temperatures, allowing us to build everything from fire tongs to furnaces out of it. In contrast to most substances, you can also magnetize iron, making it useful in the creation of electric motors and generators. Finally, there certainly aren’t any iron shortages to worry about. The Earth’s crust is 5 percent iron, and in some areas, the element concentrates in ores that contain as much as 70 percent iron.

When you compare iron and steel with something like aluminum, you can see why it was so important historically. To refine aluminum, you need access to huge quantities of electricity. Furthermore, to shape aluminum, you have to either cast it or extrude it. Iron, however, is much easier to manipulate. The element has been useful to people for thousands of years, while aluminum really didn’t exist in any meaningful way until the 20th century.

­Fortunately, iron can be created relatively easily with tools that were available to primitive societies. There will likely come a day when humans become so technologically advanced that iron is completely replaced by aluminum, plastics and things like carbon and glass fibers. But right now, the economic equation gives inexpensive iron and steel a huge advantage over these much more expensive alternatives.

The only real problem with iron and steel is rust. Fortunately, you can control rust by painting, galvanizing, chrome plating or coating the iron with a sacrificial anode, which corrodes faster than the stronger metal. Think of this last option as hiring a bodyguard to take a bullet for the president. The more active metal has to almost completely corrode before the less active iron or steel begins the process.

­Humans have come up with countless uses for iron, from carpentry tools and culinary equipment to complicated machinery and instruments of torture. Before iron can be put to any of these uses, however, it has to be mined from the ground.

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WHAT IS A HOMOLOGOUS SERIES?

A homologous series is a group of compounds that are made of the same elements and share some of the same properties and features but have different numbers of atoms in their molecules. Alkanes, alkenes and alcohols all form homologous series.

Homologous series is a series of compounds with similar chemical properties and same functional group differing from the successive member by CH2. Carbon chains of varying length have been observed in organic compounds having the same general formula. Such organic compounds that vary from one another by a repeating unit and have the same general formula form a series of compounds. Alkanes with general formula CnH2n+2, alkenes with general formula CnH2n and alkynes with general formula CnH2n-2 form the most basic homologous series in organic chemistry.

The successive members vary from each other by a CH2 unit. For example in CH4 and C2H6, the difference is -CH2 unit and the difference between C2H6 and C3H8   is also -CH2 unit. So CH4, C2H6, and C3H8 are homologs. The same thing can be observed in case of alkenes in which the first member is ethene and the successive members are C3H6, C4H8, and C5H10. They differ from each other by a –CH2 unit. Alkene formula is written as CnH2n.

All the members belonging to this series have the same functional groups. They have similar physical properties that follow a fixed gradation with increasing mass. The properties of CH3OH, C2H5OH, and C3H7OH are similar and follow a gradual change with increasing molecular mass of the successive members of the series. This is because, with the increase in the molecular mass of the compounds, the number of bonds also increases. Therefore, properties such as melting and boiling point, solubility, etc. that depend on the mass and the total number of bonds in a compound show a gradual change with an increase in molecular masses of the compounds. Chemical properties of the members of a homologous series are the same due to the fact that they all have the same functional groups in them.

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WHAT ARE CARBOXYLIC ACIDS?

Carboxylic acids contain carbon, oxygen and hydrogen. Many naturally occurring acids are carboxylic acids, such as the acid that causes nettles to “sting” and the acid in vinegar. This is called thionic acid. It is created when alcohol reacts with oxygen (oxidizes).

Carboxylic acids with low molecular weights dissolve in water because the carboxyl group forms several hydrogen bonds with water. A carboxylic acid acts both as a hydrogen bond donor through its hydroxyl hydrogen atom and as a hydrogen bond acceptor through the lone pair electrons of both oxygen atoms. The solubility of carboxylic acids, like that of alcohols, decreases with increasing chain length because long nonpolar hydrocarbon chains dominate the physical properties of the acid.

Carboxylic acids dissolve in common alcohol solvents such as ethanol. This solubility results from intermolecular hydrogen bonds between solute and solvent, and from van der Waals attractions between the ethyl group of ethanol and the nonpolar tail of the carboxylic acid. Nonpolar solvents, such as chloroform, are also excellent solvents for carboxylic acids. In these solvents, the carboxylic acids exist as relatively nonpolar hydrogen-bonded dimers that are compatible with the solvent.

Carboxylic acids are characterized by the strong absorption due to the carbonyl group in the infrared spectra of these compounds. The absorption occurs in the same region as the carbonyl groups of aldehydes and ketones, but the absorption for carboxylic acids occurs at slightly higher wavenumber, and tends to be somewhat broadened. The O—H bond of carboxylic acids absorbs in the same region as that for alcohols. However, the absorption is very much broader for carboxylic acids, and it overlaps the C—H absorptions.

Some carboxylic acids are found in fats and oils from animals and plants. They are called fatty acids. When they react with alcohol, they create compounds called esters, which give flowers their scent. Some expensive perfumes are still made by distilling the scent from flowers and preserving it in alcohol.

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WHAT IS THE CARBON CYCLE?

Carbon is an essential element in all living things. It is constantly being recycled on Earth in the carbon cycle.

Carbon is the foundation of all life on Earth, required to form complex molecules like proteins and DNA. This element is also found in our atmosphere in the form of carbon dioxide (CO2). Carbon helps to regulate the Earth’s temperature, makes all life possible, is a key ingredient in the food that sustains us, and provides a major source of the energy to fuel our global economy.

The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. Since our planet and its atmosphere form a closed environment, the amount of carbon in this system does not change. Where the carbon is located — in the atmosphere or on Earth — is constantly in flux.

On Earth, most carbon is stored in rocks and sediments, while the rest is located in the ocean, atmosphere, and in living organisms. These are the reservoirs, or sinks, through which carbon cycles. Carbon is released back into the atmosphere when organisms die, volcanoes erupt, fires blaze, fossil fuels are burned, and through a variety of other mechanisms.

In the case of the ocean, carbon is continually exchanged between the ocean’s surface waters and the atmosphere, or is stored for long periods of time in the ocean depths. Humans play a major role in the carbon cycle through activities such as the burning of fossil fuels or land development. As a result, the amount of carbon dioxide in the atmosphere is rapidly rising; it is already considerably greater than at any time in the last 800,000 years.

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HOW WAS ALCOHOL DISCOVERED?

It is likely that the effects of alcohol were discovered before the chemical! Grapes may have natural yeast on their skins that will cause the fruits or juice squeezed from them to ferment in warm conditions without the addition of further yeast. Early peoples may have discovered that fermented grape juice had an unusual flavour and effect on the body.

It’s hard to say exactly when alcohol was discovered for two reasons: 1) it was a long time ago, and 2) because you have to imagine that noting the date and time was not the first thing that occurred to the discoverers.

The first mistake that needs to be cleared up is that, while the origin may be in dispute, there is no doubt that alcohol – or fermentation, at least – was discovered rather than “invented.” One does not invent a thing that occurs naturally, as fermentation most assuredly does. (To illustrate this fact it should be pointed out that humans are not the only animals that enjoy a drink or two. A recent study published in the Proceedings of the National Academy of Sciences discusses the discovery of a few mammals in the Malaysian rainforest that drink the fermented nectar of what’s known as the bertam palm flower.)

Regarding human discovery, some paleontologists trace the origin all the way back to the Neolithic period, and some even believe that it was alcohol – or the desire for it – that prompted the first humans to take up agriculture.

Perhaps unsurprisingly, humanity’s love of alcohol has also been credited for precipitating the creation of democracy and the American Revolution. Of course, these things are spoken of in just, but if one seriously considers the integral part of alcohol in some of history’s most momentous decisions and accomplishments … well, it’s a sobering thought to say the least.

When it comes to intentional brewing the historical record is nearly as muddled. Anthropologists know people were drinking beer in Mesopotamia in 4,000 BC because there are records of it being traded, and Sumerians sang odes to it as far back as 1,800 BC, but many scientists believe the history of brewing stretches back much further.

Alcohol distillation, however, is probably a bit younger in the tooth according to most historians. Mesopotamians were known to use the distillation process, but it would take a few hundred years before the Chinese would use it to make rice liquor.

The final conclusion: booze has been around forever in some shape or form, and we’ll never really know the exact date and time that one lucky human made the discovery of a lifetime.

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