Water Anomali

Have you ever seen ice at ice tea? ice is water cooled? why ice not sink?usually solid matter have density greater than liquid matter. why it's gone? Water is a chemical compound. The compound can be interpreted as a combination of several chemical elements (atoms). The chemical formula of water is H2O, which means a combination of 2 hydrogen atoms (H) and one Oxygen atom (O). The combination of 2 or more atoms called molecules. H2O can we refer to as a water molecule. Water molecules are dipoles (has 2 poles), which are negatively charged at the oxygen atom, and positive on the hydrogen atom. So interwoven bonds between water molecules, known as Covalent bond. Beside covalent bond water also have Hydrogen bond, that is a bond between hydrogen with another element that have large electronegative difference, such as oxygen, nitrogen and fluorine.

Water has unique properties compared with other substances, other objects generally have the kind of (Rho) are great in solid form, but not with water. At 4 ° C water has the greatest density, in liquid form. When the temperature is lowered the re-shrink type, this phenomenon known as anomalous properties of water.

The secret of true anomaly of water is closely related to the continuity of living things in the hemisphere who have winters really. Anomaly has been made smaller specific gravity than water ice because ice volume is greater. Heavy water is still liquid is equal to the ice that has been frozen. The change from liquid to solid form (frozen) are not going to change the weight of these substances, however, that changes its volume increases. Because the volume of ice is greater then the density becomes smaller than water. This is why ice floats in water.

Water will begin to freeze if the molecule no longer have enough energy to escape from the bonds of hydrogen atoms (H). At 0 ° C begin to form strong bonds, in which each atom of Oxygen (O) is tetrahedrons surrounded by 4 atoms of Hydrogen (H). Which at first was not water tight molecular bond, which eventually became a crystal-perforated holes (cluster). As a result of water in solid phase (ice), this takes the form of a large volume. Increased volume of up to 10%, the species also decreased by 10% (become lighter).

Imagine if the water was not given the nature of the anomaly by the Lord so that its volume continues to shrink when cooled. What happened? The ice will sink into the water. Ice floating on water is the key course of life in the winter. The lake and the ocean turned to ice in winter, but it is only on the surface only, with no ice thickness of more than two meters. Ice in surface temperature and not be inhibited introduction of good hot or cold so the ice would be a protector of life under the lake from the air temperature is very cold. Even though the air temperature is at minus 50 ° C, below the lake water will not freeze because the ice on unprotected surfaces, and life in it was still ongoing because the temperature is not less than 0 ° C. What a great and glorious blessings.

Subhanalloh...Allohhuakbar....

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Manufacture of sulfuric acid

Sulfuric acid usually manufactured by the contact process, which is the three-step process illustrated in figure 1

Figure 1 The contact process for the production of sulfuric acid. The first step involved the oxidation of sulfur to sulfur dioxide. This is achieved by

burning sulfur in air.

S(s) + O2(g) ---> SO2(g)

The second in the process, the oxidation of sulfur dioxide to sulfur trioxide, is reversible reaction and is carried out under carefully controlled conditions to maximize the yield of SO3 produced.

2SO2(g) + O2(g) ---> 2SO3(g) + heat

As with many industrial chemical process, the conditions used are a compromise between rate, equilibrium yield and economic considerations. The equilibrium yield of SO3 is favouredby:

• Low temperatures-the reaction is exothermic.
• High pressures-the reaction leads to a decrease in the concentration of gaseous molecules.

The reaction rate is favoured by:

• High temperat ures
• High pressure
• The use of catalyst

The actual process is carried out at a temperature oa about 600oC with a V2O5 catalyst and at pressure close to one atmosphere. At this temperature using a catalyst the reaction occurs rapidly but does not occur to completion. The yield is increased by cooling the gas mixture to about 400oC and passing it over additional amounts of a catalyst. This result in almost complete conversion of SO2 to SO3. Because high yield can be obtained at atmospheric

pressure it is not necessary to use expensive high pressure equipment.

In the third step sulfur trioxide is dissolved in concentrated sulfuric acid to form oleum, H2S2O7.

SO3(g) + H2SO4(l) ---> H2S2O7(l)

Water is then added to  H2S2O7 to produce sulfuric acid.

 H2S2O7(l) + H2O(l) --->  H2SO4(l)

The SO3 is not directly absorbed in water because this reaction forms a fog of H2SO4 droplets with which it is difficult to work. The sulfuric acid produced is up 98% H2SO4 and has a concentration of about 18 mol L-1 .Both the oxidation of sulfur and sulfur dioxide are exothermic process. The large quantities of heat released in these reactions are used to generate steam and electricity and help to improve the economics of the process.

Sulfuric acid is a very important chemical in industry and is produced in greater

quantities than any other manufactured chemical. It is used in many major industries and the annual production is sometimes used as an index of a nation’s industrial activity. In Australia the annual production is about one-sixth of a tone per head of population. The major use of sulfuric acid in Australia is in the manufacture of fertilizers, but it is also used in many other industries,

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Diamond

Diamond, a crystalline form of pure carbon, is an example of a covalent network substance. It widely used in jewellery because when cut and polished it sparkles brilliantly. Experimental evidence indicates that in diamond all the C-C bonds are of the same length and all the bond angles 109.50. using this information a diamond crystal can be pictured as a single giant molecule made up of a regular network of carbon atoms extending throughout the crystal. Each carbon atom can be imagined to be at the centre of a regular tetrahedron, surrounded by four other carbon atoms atatoms at the tetrahedron, surrounded by four other carbon atoms at the corners of the tetrahedron.

In this three dimensional network of atoms, each carbon atom forms four covalent bonds by sharing electrons with each of its four nearest neighbours. The bonding electrons are tightly bound and highly localized. Thus diamond crystals are non-conductors of electricity. It is also very difficult to distort diamond, and other covalent network crystals, since this would involve breaking many covalent bonds. Consequently, diamond is extremely hard and has a very high melting and boiling point. If the highly directional bonds in diamond are subjected to extreme stress, the crystal is unable to deform in shape and it shatters. Diamond is the hardest known naturally occurring substance. Diamond unsuitable for gemstone are used in applications such as glass cutting and polishing, mineral exploration drills, dentist’ drills and record player needles.

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Household Experiment Learning Method Research

Experimental method is a method of learning in which students conduct their own experiments to prove theories that have been acquired in the classroom. Nevertheless unavailability of equipment and materials in the lab is sometimes used as an excuse vacuum laboratory activities. One effort to overcome this is to utilize the tools or chemicals that exist in the environment as a replacement of equipment and chemicals normally found in the laboratory. This method is known by the experimental method based environments.

The purpose of this study is to investigate the effect of the use of experimental methods based on chemical environment on learning outcomes of students SMA N 1 Wonosobo on the subject matter concept of oxidation and reduction reactions. All students of class X SMA N 1 Wonosobo 2009/2010 school year is a population study. The samples with cluster random sampling technique to produce the class as experimental group and X4 X5 class as the control group. Data collection was carried out in various ways ie, documentation, test, questionnaire, and observation.

The results obtained by an average of 79.76 experimental classroom learning outcomes, while the control class 73.01. The results of data analysis shows the effect of the use of environment-based experimental method to the redox chemistry student learning outcomes as indicated by the number of correlation 0.492. Conclusion of this research is the application of methods based ekeperimen learning environment influence the redox chemistry subject matter concepts class X SMA Negeri 1 Wonosobo with 24.23% contribution. Suggestions of this research is expected teachers to apply this method as a variation of learning dala, other than that teachers should also give a demonstration or explanation of what if the experiment is done by using existing materials in the laboratory

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Usefulness of Polymer

• Natural Rubber

Monomer: isoprene.

Rubber from gum-tree (Havea Brasiliensis)

Grubber gum is called latex

Latex as colloid inside water that can be precipitated by formiat acid. Natural rubber has soft characteristic, elastic, and sticky at warm. Rubber can be hardened with change its bonding by use sulfur. Its bonding will become disulfide cross bonding. Process ini ditemukan oleh Charles Goodyear pada tahun 1884 dan disebut dengan vulkanisasi

• Synthetic Rubber

It was found at World War II to supply necessary of associate.

Example : Polibutadiene, polikloropropene, and SBR

• Polybutadiene

Monomer: butadiene

Monomers from polybutadiene alike natural rubber polymer but the characteristics different with natural rubber.

Polibutadiene is strongless

It is unresistance to oil

• Polycloropropene (Neoprena)

Monomer: 2-clouro-1,3-butadiene

Neoprene resistance to oil

Used to make membuat oil tube, and some goods like that.

• SBR

Monomer: stirena (25%) dan butadiena (75%)

The most popular and it is produced at large.

SBR can be vulcanized, non oxidation, and abrasion.

Used to tyre material.

• Polyetena (PE)

Characteristics: odourless, colourless, and non toxic.

Making by Polymerization etene with high pressur 2000 atm and 200oC

Soft Characteristic, elastic and has resistance to acid and base.

Polietilene consist of two type:

• High Density Polyetilen (HDPE)

Consist of sraight chain that have compact composition. So, the bonding is closely and physical characteristic is stuffy.

• Low Density Polyetilen (LDPE)

Consist of some unit chains that uncompact composition. So, the bonding is not compact and physic characteristic is elastic and the melting point is lower.

• Polypropelin

Monomer: propene.

Characteristic: resistance to acid/ base.

Usefullness:

As removal pipeline at industry of chemistry;

Washing machine, glass.

• Polyisobutilen

Monomer: metyl propene.

Characteristic: similar natural rubber,

Usefullness:

Glue material, bracelet rubber, karet gelang, car tyre, etc.

• Polystirena

Monomer: inner of benzene (vinil benzena = stirena)

Characteristics: solid and hard

Usefullness:

Making of plastic chair, body of plane, telephone radio, sterofoom, television, etc.

• Polyvinil Klorida (PVC)

Monomer: vinil clorida.

Characteristic: content clor group, so this material resistence to corrosion, but easy to broken at low temperature.

Usefullness: Plastic pipelines.

• Polyvinil Ester

Usefullness: Glue for: skin, paper, wood and Wall paint.

• Polyvinil Polihalida (TEFLON)

Monomer: tetra fluoro etene. (PTFE)

Characteristic: Resistance to heat and chemical material, panas dan bahan kimia, Grilledless.

Polytetra fluoro etene resistance at 200oC until + 300oC

Polytri fluoro etene at - 100oC until +250oC.

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Polymerization

Polymerization is grouping micro mulecules become (monomer) menjadi macro molecules (Polymer). Based of making synthetic polymer is bonding at natural polymer.

Reaction of making synthetic polymer consist of two part. They are:

• Adition Polymerization

Chain reaction from monomers that have a double bonding at least . Chain reaction from monomers has identity with broken of double bonding.

Example:

ETENE → POLIETENE

VINIL CLORIDA → POLYVINIL CLORIDA (PVC)

• Condensation Polymerization

Reaction that happen at molecules whice have similar or different two functional groups at least, like: -OH; - COOH; - NH2. This reaction is accompanied with release micro molecule like: H2O, NH3, CH3OH

Example : polyester (dacron), polyamida (nylon 66), etc.

Usefulness of Polymer

1. Natural Rubber
2. Synthetic Rubber
3. Polybutadiene
4. Polycloropropene (Neoprena)
5. SBR
6. Polyetena (PE)
7. Polypropelin
8. Polyisobutilen
9. Polystirena
10. Polyvinil Klorida (PVC)
11. Polyvinil Ester
12. Polyvinil Polihalida (TEFLON)

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Polymer

Definition?????

• A Polymer is adalah recur chain from the long atoms, formed by bonding as identic molecul that called monomer (Greek: monos = one + meros = part)

• Although polymer usually as organic compound (have C- chain), there are also many Polymerinorganic compounds.
• A material that has many molecul consist of great recurrence units, if there are increase or decrease for some units, so it will not change the characteristics

Plastic is example of Polymer. Necessary and dependence to plastic is very high and this material become unchange by other material. The elasticity of plastics used as subtitute materials like metal, wood, etc.
Even plastic which has > 10000C is prepared to subtitute aluminium for aero plane. Plastic very usefully at 1960. At that year, world necessary of plastics reach 9 million ton per year. At 2000, world necessary of plastics reach 170 million ton.

Types of Polymer

1. Based On Bond

• Polymer Adition

          Formed by molecules that content double boding.

• Polymer Condensation

         Formed by molecules that content two functional groups in both of side main chains.

2. Based On Types of Molecular Composition

• Homopolymers :

           Polymer that formed by one type of monomer.

• Copolymers:

           Polymer thet formed by some types of monomer.

3. Based On the Characteristic to Temperature

• Termosetting:

Thermostable but can not be formed again with heating. Termosetting is polymer that has cross bonding and only can be heated once time at its production. When we heat it again, polymer will crack or broken. Example: Bekelit, Melamin, and Teflon

• Termoplastik

Soften if it be heated and harden at cool. Termoplastic is polymer that has cross bonding and can be heated again and again. If We heate it again, so it will melt and harden at cool. Example: PVC, Polietilen, and Polipropena

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Rust prevention

1. Galvanization

• Galvanization consists of coating metal with a thin layer of another such metal. Typically, zinc is applied by either hot-dip galvanizing or electroplating.
• Zinc is traditionally used because it is cheap, easy to refine and adheres well to steel. In more corrosive environments (such as at sea) cadmium may be used.

• In these cases the coating provides cathodic protection to metal,where it acts as a galvanic anode rusting in preference.

• More modern coatings add aluminium to the coating as zinc-alume, aluminium will migrate to cover scratches and thus provide protection for longer. These rely on the aluminium and zinc oxides protecting the once-scratched surface rather than oxidizing as a sacrificial anode

2. sacrificial anode

• Cathodic protection makes the iron a cathode in a battery formed whenever water contacts the iron and also a sacrificial anode made from something with a more negative electrode potential, commonly zinc or magnesium. The electrode itself doesn't react in water, but only provides electrons to prevent the iron rusting.

3. coating

• Corrosion control can be done using a coating to isolate the metal from the environment, such as paint

4. Passivation

• Given the right conditions,a thin film of corrosion products can form on a metal's surface spontaneously, acting as a barrier to further oxidation.
• When this layer stops growingat less than a micrometer thick under the conditions that a material will be used in, the phenomenon is known as passivation
• Passivation in air and water at moderate pH is seen insuch materials as aluminium,stainless steel, titanium,and silicon.

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Corrosion

What is Corrosion ?

1. Corrosion is deterioration of essential properties in a material due to reactions with its surroundings.
2. In the most common use of the word, this means a loss of an electron of metals reacting with water and oxygen.
3. Weakening of iron due to oxidation of the iron atoms is a well-known example of electrochemical corrosion. This is commonly known as rust.
4. This type of damage usually affects metallic materials, and typically produces oxides and/or salts of the original metal.
5. Corrosion also includes the dissolution of ceramic materials and can refer to discoloration and weakening of polymersby the sun's ultraviolet light.

Rusting

Rust,the most familiar example of corrosion. This electrochemical process requires the presence of water, oxygen and an electrolyte and leads to the formation of hydrated iron oxides.

Reaction:

Fe(s) -> Fe2+(aq) + 2 e-

2 H2O(l) + O2 (g) + 4 e-(aq) -> 4 OH-(aq)

Fe2+(aq) + 2 OH-(aq) -> Fe(OH)2(s)

4Fe2+(aq) + 4H+(aq) + O2(aq) -> 4Fe3+(aq) + 2H2O(l)

Fe3+(aq) + 3OH-(aq) -> Fe(OH)3(s)

2Fe(OH)3(s) -> Fe2O3•H2O(s) + 2H2O(l)

Rust factor

1. Acidity/ alkalinity of surrounding
2. Electrolyte contact
3. Condition of metal
4. Potential electrode
5. Contact with another metal

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Mass Conservation Law (Lavoisier’s Law)

Look at the burning process of paper !!! Is there decompression of mass in this process??? The most of product in the burning process of paper is gases, so the mass of substances become fewer than before. If the process occur in the closed system, so that the mass of substances before and after chemical reactions is constant.

According to Lavoisier, combustion of substances at an opened place cause the substance absorb or release other substance from and into the air, so that it cause change of the substance mass. But, in the close place there are no other substances absorbed or released during the reaction, so that mass of the object is constant relative.

Law of Conservation of Matter: During an ordinary chemical change, there is no detectable increase or decrease in the quantity of matter.

Problem 1

a. 1 gram of sodium exactly to react with 1.54 grams of chlorine gas produce sodium chloride. Calculate mass of chloride gas required to produce 7.62 grams of sodium chloride.

Solution

Because of sodium exactly to react with chlorine, then,

Sodium chloride produced = sodium mass + chlorine mass

                                               = 1 gram + 1.54 gram

                                               = 2.54 gram

To produce 7.62 grams of sodium chloride is required chlorine as much as :

                      7.62 gram x 1.54 gram = 4.62 gram

                      2.54 gram

Look this video!!!!!

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Application of Electrochemistry

One application we study about electrochemistry is protect iron from corrosion. We know that iron is widely used as housewares such as spoon, fence, etc. our motor also contains of iron. The weakness of iron is very easy to be corrosion. There are many way to protect iron from corrosion:
1. Mechanical Protected
We can protect iron by painting the iron, this the classic way. The another way is by using electroplating, coating process of iron with another metal. Note the coater metal is metal that have reduction potential less than reduction potential of iron, for example zinc. Why????because if the exfoliate zinc will be oxidation an will become anode and then iron will be reduced and become cathode. and the mini Galvani is not progress and corrosion is stopped.
the reaction is:

2. Cathode Protection
This process using the metal that have reduction potential greater than iron such as. This method is widely used as protection of tower or water pipe. To protect tower or water pipe usually use magnesium that connected with wire. magnesium will be oxidation and iron will be reduction the reaction is:

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Factors that Influence Reaction Rate

Basically, reaction rate is influenced by several factors:

1. Surface are

2. Concentration

3. Temperature

4. Pressure

5. Catalyst

a. Surface Area

The reaction rate is influenced by the surface area between reactants. A solid will react more quickly if its surface is widened by changing its form bar to powder or making the size smaller. The reaction rate increase happens because smaller pieces of the same mass of solid have a greater surface area compared to larger pieces of the solid. So the collision of the solid which have the small pieces is more than large pieces.

b. Temperature

The change in temperature will affect the reaction rate. Generally, the increase of temperature will increase the reaction rate. The increasing of temperature causes kinetic energy of reactant molecules increase, so its kinetic energy has higher point than its activation energy (Ea) or kinetic energy can reach activation energy (Ea). Generally, for each 10º C increasing of temperature, the reaction rate of the second reaction will be twice as fast as the initial reaction.

c. Concentration

The concentration of solution affect the reaction rate. Increasing the concentration of reactants will increase the frequency of collision among the reactants particles. This is because in a concentrated solution, the distance among particles is relatively close, so they are easy to collide.

d. Pressure

More reaction in daily life using reactants on gas state. The reaction rate of this reaction is influence by pressure. The increasing pressure will be decrease volume and increase concentration. So, the reaction rate of this reaction will be increase.

e. Catalyst

Catalyst is a substance that increase the rate of chemical reaction without its self undergoing any change.

Example: using MnO2 on the dissociation of H2O2

2 H2O2(aq) → 2H2O(l) + O2(g)

At room temperature, reaction is happened very slowly. However, reaction will be happened very strong after adding FeCl3

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