Category: Chemistry Notes PPT

[Chemistry Class Notes] Iron Pdf for Exam

Appearance lustrous metallic with a grayish tinge
Standard atomic weight A(Fe) 55.845(2)[1]
Atomic number (Z) 26
Group group 8
Period period 4
Block d-block
Element category   transition metal
Electron configuration [Ar] 3d6 4s2
Electrons per shell 2, 8, 14, 2

Iron has an atomic number 26 with an element symbol Fe (Ferrum) and it’s the first metal of the transition series.Not only Iron can be easily found on the earth core and the surface of it but also it is the most common metal on the earth surface. In addition, from all the other metal from the list, Iron is the fourth common element found on the earth surface.

Like the other groups 8 elements, ruthenium and osmium, iron exists to have in a wide range of oxidation states, −2 to +7, although +2 and +3 are the more common. Elemental iron occurs in shooting stars and other less oxygen environments, but it gets charged up with oxygen and water. Fresh iron surfaces appear shinny silvery-gray but oxidize in standard air environment to give hydrated iron oxides, most commonly known as rust. Unlike the metals that form passivity oxide layers, iron oxides occupy supplementary volume than the metal and thus flake off, exposing fresh surfaces production for corrosion.

Industrial routes

The production of iron or steel is a process done in two main stages. In the first stage pig iron is created in a blast furnace. On the other hand, it may be directly reduced. In the second stage, pig iron is transformed to wrought iron, steel, or cast iron.
For a limited method when it is needed, pure iron is produced in the laboratory in less quantities by reducing the amount of pure oxide or hydroxide with hydrogen or forming iron pent carbonyl and heating it to 250 °C so that it decomposes to form pure iron powder. Other method is electrolysis of ferrous chloride onto an iron cathode

Blast furnace processing

Industrial iron making starts with iron ores, principally hematite, which has a nominal formula Fe2O3, and magnetite, with the formula Fe3O4. These ores are reduced to the metal by treatment with carbon which is called as carbothermic reaction. The adaptation is typically conducted in a blast furnace at temperatures of about 2000 °C. Carbon is provided in the form of coke. The process also contains a flux such as limestone, which is used to eliminatesiliceous minerals in the ore, which would otherwise clog the furnace. The coke and limestone are fed into the top of the furnace, while a massive blast of air heated to 900 °C, about 4 tons per ton of iron,[116] is forced into the furnace at the bottom.

In the furnace, the coke reacts with O2 in the air blast to create CO (Carbon monoxide):

2 C + O2 → 2 CO

The carbon monoxide reduces the iron ore (in the chemical equation below, hematite) to molten iron, transforming to carbon dioxide in the process:

Fe2O3 + 3 CO → 2 Fe + 3 CO2

Some iron at high temperature bottom part of the furnace reacts directly with the coke:

2 Fe2O3 + 3 C → 4 Fe + 3 CO2

The flux that tries to melt impurities in the ore is principally limestone (calcium carbonate) and dolomite (calcium-magnesium carbonate). Other fluxes are used on the details of the ore. At thehigh temperature of the furnace the limestone flux decomposes to calcium oxide (also known as quicklime):

CaCO3 → CaO + CO2

Then calcium oxide mixes with silicon dioxide to create a liquid slag.

CaO + SiO2 → CaSiO3

The slag dissolve sat the high temperature of the furnace. In the base of the furnace, the molten slagfloats on top of the denser molten iron and apertures in the corner of the furnace are opened to run off the iron and the slag individually. The iron, once cooled, is called pig iron, while the slag material can be used in road construction or to improve mineral-poor soils for agriculture.

Direct iron reduction

Due to environmental concerns, other methods of producing iron have been developed. 

Two major reactions contain the direct reduction process:

Natural gas is to some extent oxidized (with heat and a catalyst):

2 CH4 + O2 → 2 CO + 4 H2

Iron ore is next treated with the gases in a furnace, creating solid sponge iron:

Fe2O3 + CO + 2 H2 → 2 Fe + CO2 + 2 H2O

Silica is discarded by adding a limestone flux as described above.

Characteristics

Physical properties
Phase at STP solid
Melting point 1811 K ​(1538 °C, ​2800 °F)
Boiling point 3134 K ​(2862 °C, ​5182 °F)
Density (near r.t.) 7.874 g/cm3
when liquid (at m.p.) 6.98 g/cm3
Heat of fusion 13.81 kJ/mol
Heat of vaporization 340 kJ/mol
Molar heat capacity 25.10 J/(mol·K)
Vapor pressure

Mechanical properties

The properties of iron and its alloys can be simplified using a variety of tests, including the Brinell test, Rockwell test and the Vickers hardness test. The data on iron is so reliable that it is often used to calibrate to compare tests. Nevertheless, the mechanical properties of iron are drastically affected by the different results of purity: pure, individual crystals of iron are less hard than aluminum,and the purest industrially produced iron (99.99%) has a toughness of 20–30 Brinell. An increasing in the amount of carbon content will cause a significant increase in the toughness and tensile strength of iron. Highest hardness of 65 Rc is achieved with a 0.6% carbon content, although the alloy has low tensile strength. Due to the softness of iron, it is much simpler to work with than its heavier congeners ruthenium and osmium. According to which its significance for environmental cores, the physical properties of iron at high pressures and temperatures have also been studied widely. The form of iron that is steady under normal conditions can be subjected to pressures up to 15 GPa before ittransform into a high-pressure form, as described in the next section.

Chemistry and compound

Iron shows different attributeof chemical properties of the transition metals, namely the tendency to form variable oxidation states differentiated by steps of one and a very large coordination and organometallic chemistry: certainly, it was the discovery of an iron compound, ferrocene, that revolutionized the latter field in the 1950s. Sometimes iron considered as a prototype for the entire building block of transition metals, due to its loads and the immense role it has played in the technological progress of humanity. In its configuration 26 elements are arranged [Ar]3d64s2, of which the 3d and 4s electrons are close in energy.
It forms compounds mainly in the +2 and +3 oxidation states. Usually, iron (II) compounds called ferrous, and iron(III) compounds ferric. It also occurs in top oxidation states, e.g. the purple potassium ferrate (K2FeO4), which has iron in its +6-oxidation state. Although iron(VIII) oxide (FeO4) has been claimed, the result could not be produced again and such a species (at least with iron in its +8-oxidation state) has been found to be unlikely computationally. But, one form of anionic [FeO4]– with iron in its +7-oxidation state, along with an iron(V)-peroxo isomer, has been found by infrared spectroscopy at 4 K after co condensation of laser-ablated Fe atoms with a mixture of O2/Ar.Iron (IV) is a general intermediate in many biochemical oxidation reactions. Numerousorgano iron compounds have formal oxidation states of +1, 0, −1, or even −2. The oxidation states and other bonding properties are often studied using the technique of Mössbauer spectroscopy.Many mixed valence compounds contain togetheriron (II) and iron (III) centers, such as magnetite and Prussian blue (Fe4(Fe [CN]6)3).The last is used as the traditional “blue” in blueprints.

Iron stands first of the transition metals that isunable to reach its group oxidation state of +8, although its heavier congener’s ruthenium and osmium can, with ruthenium having more difficulty than osmium. Ruthenium exhibits an aqueous cationic chemistry in its low-down oxidation states parallel to that of iron, but osmium does not, favoring high oxidation states in which it forms anionic complexes. In the other half of the 3d transition series, vertical similarities least on the groups compete with the horizontal similarities of iron with its neighbor’s cobalt and nickel in the periodic table, which are ferromagnetic at room temperature and contribute to similar chemistry. As such, iron, cobalt, and nickel are sometimes combined as the iron triad.

Applications

Iron is used in various sectors such as electronics, manufacturing, automotive, and construction and building.

The following are the application areas of iron:

  • • As the main constituent of ferrous metals/alloys and steels

  • • Combine with carbon, nickel, chromium and various other elements to form cast iron or steel

  • • In magnets

  • • In fabricated metal products

  • • In industrial machinery

  • • In transportation equipment

  • • In instruments

  • • In toys and sport goods

    • [Chemistry Class Notes] Isotopic Mass Pdf for Exam

    Introduction

    An atom can be composed of electrons, protons, neutrons. The total number of protons present in an atom is referred to as the atomic number. Moreover, the sum of the number of neutrons and protons is called the mass number. In any atom, the number of protons is continually equal to the total number of electrons, making it neutral because of the equal and opposite charges of both electrons and protons.

    Expressing Atomic Mass

    The atomic mass can be expressed using unified atomic mass units (u). A few of the atoms hold the same number of protons but with a different mass number because of many neutrons, and these are called isotopes. For instance; 3 hydrogen’>isotopes of hydrogen can be given as deuterium (D), hydrogen (H), tritium (T).

    They contain the same atomic number, whereas the mass numbers are different, which are 1, 2, 3, respectively. Isotopes can be found in different percentages in nature. A few of the isotopes can be found in abundance, but a few of them decay and undergo radioactivity continually in nature. For suppose; C-12 is given as the most abundant isotope of carbon, and, on the other side, C-14 is a radioactive isotope of it, each with a half-life of 5500 years.

    Isotopic Mass Definition

    At the macroscopic level, most of the mass measurements of pure substances give the mass of an isotope mixture. We can also say, in other words, that mixtures are not pure, but of all known mixture like the oxygen molecule’s macroscopic mass does not correspond to the microscopic mass.

    The macroscopic mass indicates a certain isotopic distribution, whereas the microscopic mass refers to the mass of the most common isotope of oxygen, O-16. It should be remembered that the macroscopic mass can also be called either atomic weight or molecular weight.

    How to Find Isotopic Mass?

    As we all know, isotopes are atoms that have the same atomic number but with different numbers because of the different neutron numbers. The mass number of an element is given as a whole number, whereas the atom’s actual mass is not a whole number except for the carbon-12.

    For suppose, the atomic mass of Lithium is given as 6.941 Da. Based on the abundance of isotopes, we can calculate the average atomic mass and isotopic mass of an element. The average mass of the element E is expressed as:

    m(E)=n=1m(In) p(In)

    For example, the abundance and mass of isotopes of Boron can be given as follows.

    S. No

    Isotope In

    Mass m (Da)

    Isotopic Abundance p

    1

    10B

    10.013

    0.199

    2

    11B

    11.009

    0.801

    The average mass of the Boron is calculated as follows.

    m(B) = (10.013 0.199) + (11.009 0.801)

    =(1.99) + (8.82)

    = 10.81 Da

    Relative Isotopic Masses

    It is not easy to express an element’s mass since relative isotopic masses are one of the best methods to express the known elements’ mass. We can define it as ‘Ar’;

    Ar = m/mu

    The relative isotopic mass is given as a unitless quantity concerning some standard mass quantity. The relative atomic mass of elements is taken as the atom’s weighted mean mass of an element to that of the mass of 1/12 of the mass of an atom in the C-12 element.

    In the same way, the relative isotopic mass is referred to as the atom’s mass of an isotope concerning the mass of 1/12 of the mass of an atom in the C-12 element. The isotopic abundances can be used to calculate the isotopic weights and average atomic weight.

    Average Isotopic Mass

    The percentage of isotopic mass and abundance can be used to calculate the average isotopic mass. For instance, two isotopes of Nitrogen are given as N-14, N-15, and Nitrogen’s average isotopic mass can be given as 14.007. The percentage abundance of both the isotopes is calculated as follows.

    14.003074 x Х + 15.000108 x 1 – Х = 14.007

    14 x Х+ 15 x 1 – Х = 14.007

    X = 15 – 14.007 = 0.993

    1 – X = 0.007   

    Thus, 99.3 % would be the percentage abundance of N-14, whereas, for N-15, it would be 0.7%. In the same way, the copper’s average isotopic mass is given by 63.546, and the atomic mass of Cu-63 is given as 62.929 amu, and the Cu-65, as 64.927 amu, where the resultant abundance percentage would be given as follows.

    62.9296 x Х + 64.9278 x 1 – Х = 63.546

    Therefore, x = 0.6915

    Thus, 69.15 % would be the percentage abundance of Cu-63, whereas the rest would be Cu-65.

    Uses of Isotopes

    A few of the uses of Isotopes can be given as follows.

    • A few of the isotopes are very useful and can be used widely in various chemical and medical industries.

    • Isotopes also contain similar chemical properties because they contain the same electron number and their shell arrangement.

    • The physical properties of isotopes vary and they also depend on their masses.

    [Chemistry Class Notes] Lactic Acid Pdf for Exam

    Lactic acid, also known as lactate, is a chemical byproduct of anaerobic respiration. It refers to a process where cells produce energy without having oxygen around. Lactic acid gets produced in yoghurt by some bacteria. It is also present in your gut and blood. Your muscles and red blood cells often deposit the lactate into your blood. So, lactic acid is an organic one. It’s a chiral molecule, and it has two optical isomers, which are L-lactic acid and D-lactic acid. The presence of a carboxyl group adjacent to the hydroxyl group makes lactic acid an alpha-hydroxy acid. In this article, you can learn about lactic acid structure, its definition, uses, and sources.    

    What is Lactic Acid?

    Lactic acid is one of the organic acids. The chemical formula of the lactic acid is C3H6O3. It has two optical isomers, Levo and Dextro, making itself a chiral molecule. L-isomers are commonly present among living organisms. The lactic acid has a significant part in various biochemical processes. It gets produced by the muscles during intense activity. 

    Lactic acid is soluble in water. It looks white in its solid-state and becomes colourless in the liquid state. Milk acid is another name of lactic acid. When lactose or milk sugar undergoes fermentation, the lactic acid gets produced. You can also find it in other dairy products like cottage cheese, yoghurt, etc. 

    Just so you know, a Swedish chemist, named Carl Wilhelm Scheele, isolated the lactic acid from milk for the first time in 1780. Also, the soluble salt of lactic acid, such as calcium lactate can act as a source of calcium. The PH of 1 mM of lactic acid is nearly 3.51. You can learn more about lactic acid as below. 

    Structure of Lactic Acid

    Below you can find the structural representation of lactic acid or C3H6O3.  

    (Images to be added soon)

    The extended formula of lactic acid is CH3CH(OH)CO2H, and it has a molar mass of 90.08 g/mol. Since a single carbon houses hydroxyl group (-OH) and carboxylic group (-COOH), the molecule gets classified as alpha-hydroxy acid. The central carbon is a chiral as it appears and the other two substituent groups are a hydrogen atom on a methyl group (-CH3). It results in two different structures: L-lactic acid (+) and D-lactic acid (-).

    Properties of Lactic Acid

    • Lactic acid is colorless or yellow syrupy, during its liquid state. In solid form, you can find it in the white powder. 

    • The molecular weight or molar mass of lactic acid is 90.08 g/mol. And it’s PH level is 3.51 per 1 mM of lactic acid.

    • The melting point of lactic acid is 530 Celsius, and the boiling point is 1220 Celsius. It is soluble in water and ethanol. 

    • Lactic acid is corrosive to any metals and tissue. Thus, overuse and overconsumption of the lactic acid can come with severe side effects. 

    Uses of Lactic Acid

    There are numerous lactic acid uses, and the first thing to note is that your body can produce lactic acid on its own. But, there is a significant requirement for industrially produced lactic acid. It can get formed using a synthetic process or fermentation. The latter involves usage of nutrients like amino acids, vitamins, peptides, glucose, and salt. These nutrients get combined with microbes, which further uses nutrients to give out lactic acid. 

    Once the lactic acid is ready, it can be used for various purposes as below. 

    • Personal products and healthcare products

    • Food preservatives

    • Dairy products, like yoghurt

    • Cleaning, laundry, and dishwashing products

    • Paint and coating additives

    • Furniture care products

    • Textile dyeing and leather tanning

    • Pharmaceuticals  

    Applications of Acids and Basic Substances

    Due to the different properties of acids and bases, they have a significant role in real-life applications. Some of the applications are- 

    Applications of Acid Substances

    • Citric acid is a key ingredient in lemons and oranges. Acids can also be utilized to preserve food.

    • Sulfuric acid is widely used in car batteries, which are commonly used to start the engines of automobiles.

    • Acids are used in the industrial production of explosives, dyes, and fertilizers.

    • Phosphoric acid is one of the key ingredients in many soft drinks.

    • Vinegar is a diluted form of acetic acid and it features several home applications like preserving food, etc.

    Applications of Basic Substances

    • Ammonium hydroxide is one of the most important reagents used in laboratories.

    • Any extra acidity in the ground (soil), could be neutralized by utilizing slaked lime.

    • Ca(OH)2 (also known as slaked lime or calcium hydroxide) is used to make dust which is used for bleaching powder.

    • Calcium Hydroxide is used to make dry mixes which are utilized in design or artwork.

    • The production of soap and paper requires the utilization of salt (sodium hydroxide).

    • NaOH is utilized in the making of rayon.

    • Magnesium hydroxide(also referred to as milk of magnesia) is usually used as a laxative and it also decreases any extra acidity in a human’s stomach. This property qualifies it to be an antacid.

    [Chemistry Class Notes] Lead Acid Battery Pdf for Exam

    A lead acid battery, also known as a lead storage battery is the oldest kind of rechargeable battery. The battery is common as an energy storing device. The lead acid battery was invented in the year 1859 by Gaston Plante, who was a French physicist. There are still many applications that make use of lead-acid batteries. These find wide usage in vehicles where the battery can provide high current for winding power.

    Even though the lead-acid batteries are highly reliable, these have a minimal life. These are also heavy to ship and composed of many toxic materials that require some unique methods of removal at the end of their life. The response time is good, and the power density of this kind of battery is moderate. Depending on the technology of power conversion, the lead-acid batteries can accept or supply energy almost instantaneously. Lead-acid batteries get affected by the temperature, and this is why they need maintenance to maximize their life expectancy. The above explanation lets you understand the basics about what is a lead acid battery.

    What is a Sealed Lead Acid Battery?

    The sealed lead acid battery is a 12-volt motorcycle battery and has six cells and is made up of a plastic case. Each cell contains a set of positive and negative plates that are immersed in a solution of dilute sulphuric acid, which is known as the electrolyte. Every cell has around 2.1 volts when it is fully charged. The six cells are connected to provide a fully charged 12.6-volt battery.

    So how is it possible to stick the lead plates into the sulphuric acid and produce electricity? The battery makes use of an electrochemical reaction that converts the chemical energy into electrical energy. Each of the cells has plates that resemble a small square tennis racket. These are made with lead calcium or lead antimony. A paste that is referred to as active material is bonded to the plates. Sponge lead is used for the negative plates, and lead dioxide is used for the positive plates. When there is an electrical load that is placed across the terminals of the battery, then it is in the active material that the chemical reaction with the sulphuric acid takes place.

    Know the Chemical Reaction Behind Discharging

    When the battery is in the discharged state, then the positive, as well as the negative plate, becomes lead (II) sulphate (PbSO4). The electrolyte loses the dissolved sulphuric acid, and this is now mostly water. The discharge process gets driven by the electron conduction that occurs from the negative plate back to the cell in the positive plate. This happens in the external circuit.

    Here is the Negative plate reaction:

    Pb(s) + HSO4–(aq) → PbSO4(s) + H+(aq) + 2e–

    Here is the Positive plate reaction:

     PbO2(s) + HSO4–(aq) + 3H+(aq) + 2e– → PbSO4(s) + 2H2O(l)

    The overall reaction occurs before combining the positive and negative reactions:

    Pb(s) + PbO2(s) + 2H+(aq) + 2HSO4–(aq) → 2PbSO4(s) + 2H2O(l)

    Understand the Charging of the Lead Acid Battery

    Chemical energy is stored in the lead acid battery, which is converted into electrical energy when required. The energy conversion from chemical to electrical is known as lead acid battery charging. When the electric power gets changed to chemical energy, then this is discharging.

    The sulphuric acid that is present in the lead acid battery decomposes, and this is why it has to be replaced. If the battery spends a lot of time in its discharged state, then this causes a buildup of the chemical, which is not easy to remove. The lead acid batteries are usually charged using an external source of current.

    During the process of charging, because of chemical changes, the current passes into the battery. Any lead acid battery may use two kinds of charging methods. These are constant voltage charging or constant current changing.

    Know the Chemical Reaction for Recharging

    The lead acid battery can also be recharged. When the battery is in the charged state, then every cell contains the negative plate of the element Pb or lead and the positive plate of PbO2 or lead(IV) oxide. The electrolyte contains approximately 4.2M of H2SO4 or sulfuric acid.

    In the recharging process, the electrons are forcibly removed from the positive plate, and they are introduced forcibly in the negative plate. This is done by the source of charging.

    Here are the chemical reactions that occur in the respective plates.

    Negative plate reaction

     PbSO4(s) + H+(aq) + 2e– → Pb(s) + HSO4–(aq)

    Positive plate reaction

     PbSO4(s) + 2H2O(l) → PbO2(s) + HSO4–(aq) + 3H+(aq) + 2e–

    The overall reaction when the negative and the positive plate reactions are combined is:

    2PbSO4(s) + 2H2O(l) → Pb(s) + PbO2(s) + 2H+(aq) + 2HSO4–(aq)

    This is the reverse of the discharge reaction.

    It is important to note that if the battery is overcharged, then this will lead to the formation of oxygen gas and hydrogen gas, which are the byproducts. These gases cause a loss of the reactants because of these escapes from the battery.

    [Chemistry Class Notes] Liquefied Petroleum Gas – LPG Pdf for Exam

    Liquefied petroleum gas (LPG), which is also known as LP gas, is any of multiple liquid mixtures of the volatile hydrocarbons propane, propene, butane, and butene. It was used from the early 1860s as a portable fuel source, and the production and consumption of this gas for both industrial and domestic use have expanded ever since. A typical commercial mixture can also contain ethylene and ethane, and a volatile mercaptan as well, which is an odorant added as a safety precaution.

    (Image to be added soon)

    About LPG

    Liquefied petroleum gas – LPG is recovered from the “wet” natural gas (the gas with the compounds of condensable heavy petroleum) by absorption. The recovered product has a low boiling point and should be distilled to remove the lighter fractions, and then it is treated to remove carbon dioxide, hydrogen sulfide, and water. The resultant product can be transported by pipeline and by building seagoing tankers, especially. Transportation by rail, barge, and truck has also developed, specifically in the United States.

    LPG reaches the domestic consumers in cylinders at relatively low pressures. The largest part of the LPG, which is produced, can be used in the central heating systems, and the next largest one as a raw material for chemical plants. Commonly, LPG can be used as fuel for gas cooktops and ovens, gas barbecue grills, portable heaters, and gas fireplaces. LPG water heaters are common in Europe. It is also used as backup generators and engine fuel. Unlike diesel, LPG is stored nearly indefinitely without any degradation.

    Global Production

    In 2015, the Global LPG production reached over 292 million metric tons per year, while global LPG consumption rose to around 284 mn t per year. 62% of the LPG is extracted from the natural gas, where the rest can be produced by the petrochemical refineries from crude oil. 44% of global consumption is present in the domestic sector. The leading producer and exporter of LPG are the USA.

    Security of Supply

    Due to the oil-refining and natural gas industry, Europe is considered as almost self-sufficient in LPG. The security of supply in Europe is further safeguarded by:

    • a wide range of sources, which are both inside and outside of Europe;

    • a flexible supply chain through rail, road, and water with a number of routes and entry points into Europe

    As per 2010–12 estimates, the proven world reserves of the natural gas, from which the major amount of LPG is derived, stand at 300 trillion cubic meters (which is 10,600 trillion cubic feet). Added to the LPG, which is derived from the cracking crude oil, these amounts subject to a major energy source which is untapped virtually and has massive potential. The production continues to grow at an average rate of 2.2%, annually, and virtually assuring that there is no demand outstripping supply risk in the foreseeable future.

    Comparison with Natural Gas

    LPG-based SNG can be used in the emergency backup systems for several industrial, public, and military installations and several other utilities use LPG peak shaving plants in times of high demand to make up shortages in the natural gas, which is supplied to their distributed systems. LPG-SNG installations can also be used during the initial gas system introductions when the distribution infrastructure present in the place before gas supplies are connected. Developing Indian and China markets (among others) use LPG-SNG systems to build up the customer bases before expanding the existing natural gas systems.

    Natural gas or the LPG-based SNG with localised storage and the piping distribution network to the households for catering to every cluster of 5000 domestic consumers is planned under the first phase of the city gas network system. This would eliminate the last mile of LPG cylinders road transport, which is a cause of safety and traffic hurdles in the Indian cities. However, these localised natural gas networks are operating successfully in Japan with the feasibility to get connected to a wider network in both cities and villages.

    Environmental Effects

    Let us discuss the Environmental effects of LPG.

    Commercially available Liquid Petroleum Gas (LPG), is currently derived primarily from fossil fuels. Also, LPG burning releases carbon dioxide, which is a greenhouse gas. The reaction also forms some carbon monoxide. However, LPG does release less CO2 per unit of energy compared to oil or coal, but more than the natural gas. It emits 81% of the CO2 per kWh formed by oil, 70% to that of coal, and less than 50% of that, emitted by the coal-generated electricity distributed through the grid. Being a mix of butane and propane, LPG emits less amount of carbon per joule compared to the butane, but more carbon per joule compared to propane.

    LPG also burns more cleanly compared to the higher molecular weight hydrocarbons, since it releases fewer particulates.

    [Chemistry Class Notes] Magnesium Carbonate Pdf for Exam

    Definition

    Magnesium carbonate, as the name suggests, is a carbonate having positively charged Magnesium ion and negatively charged carbonate ion. It is an inorganic salt. 

    Before reading about Magnesium carbonates in detail, it is necessary that you know what is a salt or carbonate in chemistry. In chemistry, salt is a compound that is made up of the combination of a positively charged compound and a negatively charged compound. In other words, salt is a compound made up of anion and cation. However, the overall charge of the salt is zero – it is neutral since salts must have an equal number of anions and cations. Inorganic salt is different from organic salts. It does not have any C-H bonds. Carbonate is that compound that is made up of Carbon and Oxygen. Its Chemical formula is CO₃²⁻.

    Magnesium Carbonate: In Detail

    So now that you know the background, let us talk about MgCO₃ in detail. As said, MgCO₃ is a salt. Why is it a ‘salt?’ – This is because the compound is made up of MG²⁺ and CO₃²⁻, the two ions negate each other because of the equal amount of positive and negative charge. 

    MgCO₃ is mostly obtained by mining Magnesite. Magnesite is a form of MgCO₃. Magnesite is a mineral that occurs as white or grey crystalline solid. Magnesite is the altered form of Magnesium-rich rocks. The miners do not need to drill too much deep inside the earth to mine Magnesite. As a result, Magnesite is easy to mine. Magnesite is processed to synthesize magnesium carbonate. 

    The salt can also be found in the form of dihydrate mineral known as barringtonite. Found first in Barrington Tops, Australia, this dihydrate mineral is formed from the leaching of basalt. There is also the trihydrate form of MgCO₃ known as the nesquehonite which is quite similar to barringtonite. Another hydrated form of magnesium carbonate is lansfordite. This one was first found in Lansford. And it is a pentahydrate. As you can guess from the names, the dihydrate has 2 moles of H₂O along with MgCO₃, the trihydrate form has 3 moles and the pentahydrate form of magnesium carbonate has 5 moles of H₂O.

    The above minerals are all natural sources of magnesium carbonate; but what about the industrial manufacturing of MgCO₃? Yes, it is also possible. In the laboratory, the reaction between any (water-soluble) magnesium salt and sodium bicarbonate will result in the production of MgCO₃.

    Properties of Magnesium Carbonate

    The key properties of magnesium carbonate are:

    • Magnesium carbonate can either appear as bulky white powder if it is heavy or as light white powder if it is light.

    • MgCO₃ is odourless but as the Chemical Book website points out – because of its high absorption capacity, it can absorb many types of odour.

    • MgCO₃ cannot dissolve in water or alcohol but it can dissolve in inorganic acids.

    Group 2 Metal Carbonates

    If you look at Group 2 in the periodic table, you will find six metals. All these metals are known for their thermal decomposition properties. It means that the carbonates of the metals of this group will undergo thermal decomposition and spit out their corresponding metal oxides and CO₂.

    This is also true for the carbonate of magnesium. When magnesium carbonate is heated, it dissociates into MgO and CO₂.

    MgCO₃ → MgO + CO₂

    Again, similar to other group 2 metals, magnesium carbonate gives out CO₂ and H₂O when it reacts with acids like sulphuric acid and hydrochloric acid.

    Here goes the summary of the properties of magnesiun carbonate:

    Summary of Magnesium Carbonate Properties

    Properties of Magnesium Carbonate 

    Heavy MgCO₃ appears as grainy powder while light MgCO₃ appears as a light thin powder.

    Although magnesium carbonate is odourless, due to its high absorption power, it can absorb odours from other sources.

    MgCO₃ is insoluble in water or alcohol but it can dissolve in inorganic acids

    Just like the other Group 2 metal carbonates, MgCO₃ breaks into MgO and Carbon dioxide when heated.

    Just like the other Group 2 metals, magnesium carbonate releases CO₂ and H₂O when reacted with acids.

    The molecular weight of magnesium carbonate in its anhydrous form is 84.3139 g/mol.

    The molecular weight of heavy, hydrated form of MgCO₃ is 383.32

    The molecular weight of light, a hydrated form of MgCO₃ is 365.30. 

    The decomposition temperature of MgCO₃ is 350-degree Celsius.

    Uses of Magnesium Carbonate 

    The top applications of magnesium carbonate are as follows: 

    • The main usage of MgCO₃ is the production of Magnesium Oxide. Magnesium oxide is used in the medical field to mitigate heartburn and acid reflux. It aids the digestive system. It is also used as a mild laxative.

    • Because of its insulating properties, MgCO₃ is used as fireproofing.

    • Because of its absorption properties and pH balancing power, it is used in the cosmetic industry.

    • Because of being an antacid, it is also used in toothpastes to get rid of acid formation in the mouth.

    • It is used to stiffen ink without ruining its colour.

    • MgCO₃ is also used in the filtration process.

    Magnesium Carbonate in the Medical Industry 

    Today the general public is aware of magnesium carbonate because of its medicinal properties. People who have low amounts of magnesium in the blood, take the magnesium carbonate pills. Magnesium carbonate is extremely useful when it comes to the removal of acid from the stomach. It is highly effective in treating acidity, heartburn and indigestion. However, with all its usefulness, MgCO₃ is not devoid of harmful effects. Consumption of too much magnesium carbonate can result in addiction.

    Therefore, to recap what we have learnt so far:

    • MgCO₃ is a carbonate or salt having Magnesium cation and negatively charged carbonate ion. It is naturally found in the form of minerals like Magnesite or dolomite.

    • The Mg in magnesium is positively charged and the CO₃ is negatively charged. The two ions make the compound neutral as a whole.

    • In the lab, MgCO₃ can be obtained with the reaction between any magnesium salt that is soluble and sodium bicarbonate.

    • Magnesium carbonate can either appear as granular white powder if it is heavy or as light white powder if it is light.

    • It is an odourless compound but can absorb odours from other sources.

    • The molecular weight of magnesium carbonate in its anhydrous form is 84.3139 g/mol.

    • MgCO₃ starts decomposing at 350-degree celsius.

    • MgCO₃ is primarily used to obtain magnesium oxide.

    • MgCO₃ is used to make antacids.

    • It has insulating properties. That is why it is used in fireproofing.

    • MgCO₃ is also used in the water industry as a filtrating agent.

    Magnesium Carbonate is an extremely useful mineral or carbonate that has medicinal properties. The great thing about MgCO₃ is it is not that hard to mine. There are very few naturally occurring compounds that are so useful and so at the same time so easy to obtain. This is the speciality of the compound magnesium carbonate.