Methane and Iodoform

Methane and Iodoform

Methane is an organic compound consist of one carbon atom and four hydrogen with the chemical formula CH₄. This compound is the simplest compound of alkanes, and the main component of natural gas. Methane bond angle is 109.5 degrees. Burning methane in the presence of oxygen produces carbon dioxide and water.

Iodoform is an organic compound consist of one carbon atom, one hydrogen atom and three iodine atoms with the formula CHI₃. Iodoform has the characteristics of pale yellow, crystal form, including volatile substances, a characteristic odor like a hospital smell, taste sweet and analogous to chloroform. It is sometimes used as a disinfectant.

Covalent bond

Methane and Iodoform form compounds with covalently bonded, in which covalent bonding two compounds can be described or explained by the Lewis structure (electron dot formula). This formula can describe the role of valence electrons in bonds held.

Each carbon atom has 4 valence electrons are used to form covalent bonds with other atoms are described as hand ties. So the carbon atoms in carbon compounds always have a four-hand ties. In the fourth hand methane is used to bind four hydrogen atoms to another. Four hydrogen atoms form a bond with an atom C, 1 valence electrons possessed by the hydrogen atom will be donated to the carbon atoms to form bonds, while in the hands of Iodoform fourth C atoms are used to bind three iodine atoms and one hydrogen atom. Valence electrons possessed by the atoms of carbon, hydrogen atoms and iodine atoms will be used together to meet the doublet and the octet rule in the bond, so the electron configuration of atoms has been like a noble gas electron configuration. The number of hands to describe the amount of bond bond in a covalent compound. Four bond that occurs in the compound methane is four single covalent bonds as well as with Iodoform.

Simple views of the bonding in methane

There was an error comparison between the old structures and modern electronic structure of carbon, 1s² 2s² 2p_x¹ 2p_y¹. Modern structures show that there are only 2 unpaired electrons to share with atomic hydrogen, not need 4 atoms are shown in the modern structure. This will be seen more easily by using the notation of electron-in-box. Only electrons in the skin-to-2 that will be displayed. Elektron1s² is too deep inside the atom to be involved in bonding. Electron Direct only available for sharing is the 2p electron is 2p_x¹ 2p_y¹.

Promotion of electrons

When the bonds are formed, energy is released and the system becomes more stable. If carbon form 4 bonds than 2, two times more energy is released and therefore the resulting molecule becomes more stable. There are only a small energy gap between 2p and 2s orbitals, and therefore carbon provides a small amounts of energy to promote electrons from 2s to 2p a blank to allow up to 4 unpaired electrons. Extra energy released when electrons in the sub skin 2s 2p promoted to sub skin. Electron carbon atom is now said to an excited state. Now there are 4 unpaired electrons ready to bond, other problems arise. In methane all the carbon-hydrogen bonds are identical, but the electrons are in two kinds of orbitals. This allows not going to get four identical except bonds ranging from four identical orbitals.

Hybridization
            Electrons rearrange themselves again in a process called hybridization. Hybridization regulate electron into four identical hybrid orbitals called hybrid sp³ (because they are made from one s orbital and three p orbitals).

Hybrid orbital sp³ looks a bit like half the orbital p, and they arrange themselves in space so they are as far apart as possible. The core is at the center tetrahedron (triangular pyramid) with orbital pointing into the corner.

What happens when a bond is formed?

Electrons in the 1s orbital of hydrogen - a spherically symmetric region of space surrounding the nucleus in which there are few opportunities for permanent (say 95%) to find the electron. When covalent bonds are formed, the atomic orbitals (orbitals in individual atoms) combine to produce a new molecular orbital containing the electron pair that created the bond.

Four molecular orbitals are formed, looks somewhat like the original sp³ hybrids, but with hydrogen nuclei attached to each lobe. Each orbital holds 2 electrons. The principles involved - the promotion of electrons if the hybridization is needed, then, followed by the formation of molecular orbitals - can be applied to any molecule that is bound covalently.

Form of methane and Iodoform

When the sp3 orbitals are formed, they arrange themselves so that they are as far apart as possible. It is a tetrahedral arrangement, with angles 109.5 °. No change in form when the hydrogen atoms in methane and iodine atoms in Iodoform join carbon, so the methane molecules and Iodoform also tetrahedral with bond angles 109.5 °

The Phsycal Properties

Methane
Molecular formula: CH₄

Molar Mass: 16.042 g / mol

Appearance: Colorless Gas

Density: 0.717 kg / m 3 (gas, 0 °C), 415 kg / m³ (liquid)

Melting point: -182.5 °C, 91 K, -297 °F

Boiling Point: -161.6 °C, 112 K, -259 °F

Solubility in water: 35 mg / L (17 °C)

Iodoform
Molecular formula: CHI₃

Molar mass: 393.73 g / mol

Appearance: pale yellow crystals

Density: g/cm3 4008

Melting point: 123 °C

Boiling Point: 217 °C

Solubility in water: 0.1 g / L at 20 °C

Methane is the main component of natural gas, about 87% by volume. At room temperature and standard pressure, methane is a colorless gas, odorless; characteristic odor of natural gas as used in homes are made of security measures caused by the addition of an odor, often methanethiol or ethanethiol. At 1 atmosphere pressure, boiling point -161.5 °C (-258.7 °F) and melting point is -182.5 °C (-296.5 °F). This caused the methane is highly flammable and reacts violently with some halogen compounds. As a combustible gas is only a narrow range of concentrations (5-15%) in the air. Liquid methane does not burn unless experiencing high pressure (typically 4-5 atmospheres).

While the physical properties Iodoform is a form of yellow crystals sparkling. Shape up from Iodoform is hexagonal with I as its center. At room temperature and standard pressure, volatile Iodoform(sublimes), has a melting point of 119-123 0C, density 4.00 g / mile, molecular weight 393.73 g / mol. The composition of iodoform is C = 3.05 g; H = 6.266; I = 96.496. Iodoform also be decomposed by the heat effect of light and air to form CO₂, CO, I₂, H₂O. Has a smell like the smell ofhospital. It's hardsoluble in water, but easilyin alcohol, slowly soluble in petaoida atoms.

Each molecule of methane is small, consisting of four hydrogen atoms bound to a single carbon atom by covalent bonds. The molecule is shaped like a tetrahedron, with carbon atom at the center and four hydrogen atoms occupy the four corners of the tetrahedron. Unlike the water molecule, the poles and pull one another, methane molecules are non-polar and do not have much attraction for each other. This is the reason why, at room temperature, methane is a gas while the water is liquid.

Artificial synthesis

Methane was found and isolated by Alessandro Volta between 1776 and 1778 when studying the marsh gas from Lake Maggiore. In the laboratory, methane can be produced by direct reaction of carbon with hydrogen, or aluminum carbide with water. In industrial settings, the methane produced by a chemical reaction between hydrogen and common atmospheric gases. While Iodoform first made by Georges Serrulas in 1822 and identified the molecular formula by Jean-Baptiste Dumas in 1834. It is synthesized in the reaction haloform by the reaction of iodine and sodium hydroxide with one of four types of organic compounds: (i) methyl ketone: CH₃COR, acetaldehyde (CH₃CHO), ethanol (CH₃CH₂OH), and certain secondary alcohols (CH₃CHROH, where R is the group alkyl or aryl).

Chemical Reaction

The reaction of methane

The main reactions with methane are: combustion, steam reformation to syngas, and halogenation. In general, the reaction of methane is difficult to control. Partial oxidation to methanol, for example, difficult to achieve; reaction usually lasts until the carbon dioxide and water.

1. Combustion Reaction

In the combustion of methane, several steps are involved:

Methane is thought to form a formaldehyde (formaldehyde or H₂CO). Formaldehyde gives formyl radical (HCO), which then forms carbon monoxide (CO). This process is called oxidative pyrolysis:

CH₄ + O₂ → CO + H₂ + H₂O

Following oxidative pyrolysis, H₂ oxidize, forming H₂O, releasing heat. This happens very quickly, usually significantly less than one millisecond.

2H₂ + O₂ → 2H₂O

Finally, the CO oxidizes, forming CO₂ and release more heat. This process is generally slower than other chemical steps, and usually requires a few milliseconds for a reaction can occur.

2CO + O₂ → 2CO₂

Total reaction of the above reactions are as follows:

CH_4(g) + 2O_2(g) → CO_2(g) + 2H₂O_(l)      ∆H + 891 k J / mol (at standard conditions)

where the parentheses "g" stands for the form of gas and parentheses "l" stands for liquid form.
2. Hydrogen Activation

In methane, carbon - hydrogen covalent bond is one of the strongest in all hydrocarbons. In chemical terms, there are "activation barrier" high to break the CH bond. In other words, it needs enough energy to break it. However, methane is the main starting materials for the manufacture of hydrogen. Searching for catalysts that can lower the activation barrier to C-H bond of methane molecule is in the research area with significant industry.

3. Reactions with halogen

Methane reacts with all halogen in a suitable condition, as follows:

CH₄ + X₂ → CH₃X + HX

where X is a halogen: fluorine (F), chlorine (Cl), bromine (Br) or iodine (I). This reaction can continue, so CH₃X react with X₂ to produce CH₂X₂; CH₂X₂ in turn can react with X₂ to produce CHX₃, and CHX₃ can react further to produce CX₄. The mechanism for this process is called free radical halogenation. When X is Cl, this mechanism has the following format:

1. Radical generation:

The energy required comes from UV radiation or heating,

2. Radical exchange:

CH₄ + Cl • → CH₃ • + HCl                ∆H = + 14 kJ

CH₃ • + Cl₂ → CH₃Cl + Cl •              ∆H = + 100 kJ

3. Radical extermination:

2Cl • → Cl₂                             ∆H = + 239 kJ

CH₃ • + Cl • → CH₃Cl           ∆H = + 339 kJ

2CH₃ • → CH₃ CH₃                ∆H = + 347 kJ

If methane and X₂ are used in equimolar quantities, CH₂X₂, CHX₃, and even CX₄ are formed. Using a large excess of CH₄ reduces the production of CH₂X₂, CHX₃, CX₄, and thus more CH₃X is formed.

Reaction of Iodoform

Reaction of iodine and bases with methyl ketone is very reliable, that the "test Iodoform" (appearance of yellow precipitate) was used to investigate the existence of methyl ketones. This also happens when testing for the secondary alcohol (methyl alcohol).

Some of the reagent (eg hydrogen iodide) convert Iodoform for diiodomethane. Also conversion to carbon dioxide is possible: Iodoform silver nitrate reacts with water to produce carbon monoxide, are oxidized by a mixture of sulfuric acid and iodine pentaoksida. When treated with elemental silver powder Iodoform reduced, producing acetylene. After heating Iodoform decomposes to produce diatomic iodine, hydrogen iodide, and carbon.

Haloform reaction is a chemical reaction where haloform (CHX₃, where X is a halogen) is produced by complete halogenation of the methyl ketone (a molecule that contains the group R-CO-CH₃) in the presence of bases. [1] R may be H, alkyl or aryl. This reaction can be used to produce CHCl₃, CHBr₃ or CHI₃.

Haloform reaction scheme

Substrate who successfully underwent haloform reaction is methyl ketones and secondary alcohols to methyl ketones oxidizable, such as isopropanol. Halogen can be used chlorine, bromine, and iodine. Fluoroform (CHF₃) can not be made from methyl ketones by the reaction because of the instability hypofluorite haloform, but the compounds of the type RCOCF₃ do unite with the basis to generate fluoroform (CHF₃) is equivalent to the steps a second and third in the process shown above.

Mechanism

In the first step, halogen didisproportionasi with hydroxide to form a halide and hypohalite:

OH-→ X₂ XO-X-H (X = Cl, Br, I)

If the secondary alcohol is present, is oxidized to ketones by hypohalite this:

If the methyl ketone is present, reacts with hypohalite in the process of three steps:

(1)   R-CO-CH₃ 3OX-→ R-CO-3 OH-CX₃

(2)   R-CO-OH → RCOOH CX₃-CX₃

(3)   RCOOH → RCOO-CX₃-CHX₃

Detailed reaction mechanism is as follows:

In basic conditions, these ketones having keto-enol tautomerization. Enolate which electrophilic attack by hypohalite (containing halogen with a formal charge of 1).When the position has been profound halogenated α, the molecule having a nucleophilic acyl substitution by hydroxide, with a group of left-CX₃ stabilized by three electron-attractive group. The anion-CX₃ abstract protons from both carboxylic acid form, or solvents, and forms such haloform.

This reaction is traditionally used to determine the presence of methyl ketone, or oxidizable secondary alcohols to methyl ketones via Iodoform test. Currently, techniques such as infrared spectroscopy and NMR spectroscopy are preferred because they require small samples, perhaps non-destructive (for NMR) and easy and quick to perform.
Previously, it was used to generate Iodoform chloroform and bromoform and even industrial.
In organic chemistry, this reaction can be used to convert the terminal methyl ketone into the corresponding carboxylic acid.

Methane and Iodoform is an organic compound that is similar but actually different from the equally composed of atoms C and H, it's just on there Iodoform iodine atom attached to three carbon atoms hand. Both these compounds form four single covalent bonds and has the shape of tetrahedral. From his form at room temperature, gaseous methane and Iodoform form crystals.

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Beaker Glas

Beaker Glass

Beaker Glass is by definition an amorphous solid material made by fusing silica with a basic oxide. Architectural glass is made from three principal raw materials, easily found in nature: silica, lime and sodium carbonate. Beaker Glass in the form of high glass, have big diameter with the scale as long as its wall. Beaker glass have the interesting form, besides have interesting form also have the interesting function. Beaker glass is as place to dissolve the substance which does not need high correctness (qualitatively), for example reagent for the analysis of chemical qualitative or for the making of standard solution. Beaker glass have various size, there are start from 10 mL, 25 mL, 50 mL, 100 mL, until 5 Liter. Beaker glass incompatible for the making of solution which need the high correctness (quantitatively). Function of beaker glass are to measure the solution volume which do not need the high correctness (qualitatively), accommodating chemical substance, as a place for heating liquid because when heated beaker glass, it will not break although heated with the very high temperature.

Hydrologic Cycle

Water is something that is needed by living things on earth. In general, the number of water on this planet is the same though humans, animals and plants use water for many daily needs. Number of clean water does not seem limited, but actually experiencing water hydrologic cycle in which water is dirty and mixed with many substances cleaned again through natural processes.

Hydrologic cycle process ongoing that make the water into a renewable natural resource. The amount of water on earth is very much in the form of liquids, gases/vapors, and solid ice. The amount of water as if looking more and more because of ice in the polar north and south poles melting because global warming.

The water cycle or hydrologic cycle is the circulation of water that never stops the atmosphere to earth and back into the atmosphere through condensation, precipitation, evaporation and transpiration. Warm sea water by sunlight is a key process of the hydrologic cycle can be run continuously. Evaporated water, then fall as precipitation in the form of rain, snow, hail, sleet and snow (sleet), light rain or mist.

On the way to earth some precipitation may evaporate back to the top or fell in the later intercepted by plants before it reaches the ground. After reaching land, the hydrologic cycle continues to move in a continuous in three different ways:

Evaporation/transpiration, water that is at sea, on land, in rivers, in plants will then evaporate into the air (atmosphere) and then going into the clouds. In the state of saturation water vapor (clouds) it will be water spots and then it will go down (precipitation) in the form of rain, snow, ice.

Infiltration into the ground, water moves into the soil through cracks and pores of the soil and rocks into the ground water. Water can move due to capillary action or water can move vertically or horizontally below the soil surface until the water is re-entering the surface water system.

Surface Water, water moving over the soil surface close to main stream and lake; more sloping land and fewer and fewer of the pores of the soil, the greater the surface flow. Soil surface flow can be seen usually in urban areas. The rivers join each other and form a major river that brings the entire surface of the water surrounding watershed into the sea.

Surface water, either flowing or stagnant (lakes, reservoirs, marshes), and part of subsurface water will be collected and forms a stream flowing into the sea and ends. The process of water traveling in the mainland took place in the hydrologic cycle components that form the watershed system (DAS). The amount of water on earth as a whole is relatively fixed, that's changed is the form and place.