MID TEST ANSWER OF ORGANIC CHEMISTRY 1

COURSE               : ORGANIC CHEMISTRY I

CREDIT                  : 3 SKS

DAY/ TIME          : TUESDAY, NOVEMBER 13TH 2012-11-13

LECTURE              : Dr. Syamsurizal

1.     1.   a. Explain  how the concept of organic compounds from petroleum can be used as a fuel for vehicles such as car, motorbike, including air craft.

 answer:

 Petroleum is a mixture of various hydrocarbons. Oil obtained from the bowels of the earth from the remains / fossil animals buried millions of years ago that has turned into oil. The chemical structure of the Earth's oil is very heterogeneous, composed of many hydrocarbon chains of different lengths vary. Therefore, the oil brought to the Earth so that the oil refinery hydrocarbon compounds can be separated by distillation and chemical process engineering lainnya.Disana petroleum processed in stages generate the kinds of fuel earlier. The types of fuel produced is a gas, gasoline, kerosene, diesel, heavy oil (used for lubricating oils, waxes, petrochemical feed process), and the residue (used to fuel steam generating machinery, asphalt, coatings anti-leak ).
Distillation or distillation is a method of chemical separation based on differences in the speed or ease evaporate (volatility) materials.
In distillation, boiling mixture of substances that vaporize, and the vapor is then cooled back into liquid form. Substance which has a lower boiling point will evaporate first.
Distillates are commonly used for petroleum is distilled Fraksionisasiseparate liquid components, two or more, of a solution based on differences in their boiling points.  Distillation can also be used to mix with different boiling points of less than 20 ° C and working at atmospheric pressure or the pressure of this column rendah Di warming in stages with different temperatures on each license plate . Warming different aims for the purification of the distillate over plates underneath. Getting to the top, the less volatile liquid.


b. explain it how the idea of chemical compounds from petroleum can be used to make clothing and plastic and material needs of other human lives.  
answer : 
plastic created by combining monomers of petroleum which include styrene, vinyl chloride, and vinyl acetate and many more. monomers are strung together to form a polymer. Polymer made ​​by linking two monomer chains to do with methods of thermosetting and thermoplastic. In the method of thermosetting, liquid monomer is poured into molds and allowed to cool.
Liquid monomer has a permanent form so that the resulting product is durable.
With the method of thermoplastic, liquid monomer is heated and slowly molded according to the needs.
After that, the product is then cooled to a desired item.

    2.  Explain why the hydrocarbons that are asymmetrical or chiral have a variety of benefit for human being. And describe how does it the chiral centers can be formed  

a     Answer  : 

a     asymmetric or chiral hydrocarbons have many benefits for humans because of the structure itself one C atom can bind to 4 pieces of different functional groups. and functional groups can be replaced. so different from different functional groups function.

an organic molecule is called chiral molecules if there is at least one C atom that binds to four different groups. Chiral Molecules have very unique properties, namely optical properties. That is a chiral molecule has the ability to rotate the plane of polarized light in a device called a polarimeter. When four different atoms bonded to the atom. Not terdapatsimetri the molecule.

Molecules that do not have a field called chiral symmetry. The carbon atoms in which four different atoms bonded core called chiral or asymmetric carbon atom.

       3.  When the ethylene gas produced from a ripe fruit can be used to ripe other  fruits that are still unripe. How do you idea when the gas is used as fuel  gas like methane gas.

a answer  : 

oon ethylene C2H4 the formula, there is a double bond here. then fuel gases such as methane CH4, the formula does not have a bond. then that ethylene could be like methane the bond shall be terminated by way of oxidation

                4.  Aromatic compounds are marked by ease of adjacent electrons conjugated. Please explain why  an unsaturated compound which highly conjugated but is not aromatic?

a  answer  : 

u    Unsaturated compounds do have a bond with a highly conjugated electron. but as we all know that the condition is not only aromatic compounds having a conjugated electron adjacent but uga should have 6 carbon atoms connected by three single bonds and 3 double bonds that criss-cross. Three single bonds and 3 double bonds that criss-cross this is not owned by unsaturated compounds that unsaturated compounds are not aromatic

    RIZKI FITRIA

    RSA1C111011

 

 

ORGANIC ACID BASES

Before we get to the acidic organic base, we must first know what is meant by acids and bases.

Acid is a substance that has specific properties, for example, have a sour taste, can damage the surface of metal or marble flooring also often referred to as corrosive. Acid can also react with metals and produce hydrogen gas, as a simple indicator of the acidic compounds, can be used litmus paper, which can alter the acid blue litmus paper to red.

In chemistry, we can define acids as compounds that produce hydrogen ions when dissolved in a solvent (usually water) with a pH of less than 7. In the modern definition, an acid is a substance that can give a proton (H +) to another substance (called bases), or to receive a free pair of electrons from a base. Acids are generally sour taste; however, sour taste, especially concentrated acids, can be dangerous and is not recommended.

According to Brønsted-Lowry acid is a proton donor to the base. Corresponding acids and bases called conjugate acid-base pair. Brønsted and Lowry independently proposed definition, which includes substances that are not soluble in water (unlike the Arrhenius definition).

            According to the Arrhenius acid is a substance that increases the concentration of hydronium ions (H3O +) when dissolved in water. The definition was first proposed by Svante Arrhenius limits acids and bases to substances that can be dissolved in water.

In general, the acid has the following properties:

• Flavor: sour when dissolved in water.

• Touch: acid stung to the touch, especially when acid a strong acid.

• reactivity: acid reacts violently with many metals, which is corrosive to metal.

• Electrical conductivity: acid, although not always ionic, an electrolyte.

Basa is a chemical compound that absorbs hydronium ions when dissolved in air.Basa is the opposite (dual) of the acid, which is devoted to the elements / chemical compound that has a pH greater than 7. Bases can be divided into a strong base and a weak base. The power base is highly dependent on the ability of these bases release OH ions in solution and the concentration of the base solution. Bases can change red litmus to blue.

In general, the base has the following properties:

• Caustic

• It was bitter

• Slippery like soap

• pH value of more than soap

• Change the color of red litmus to blue

• Able to conduct electricity

The scale of pH (power of hydrogen) ranged from 10 to 14. Value of 7 indicates a neutral substance (no acid-no base). An acid has a pH value less than 7. Increasing pH values ​​approaching 0, the stronger the acid levels, whereas if the pH value of a substance nearly 7, the weaker acid levels (reduced). Basic compounds have a pH value greater than 7. Increasing pH values ​​approaching a value of 14, the level kebasaannya stronger.

Organic acids

Organic acids are organic compounds that have a degree of acidity (English: acidic properties). The most common organic acids are the alkanoic acid having acidity with carboxyl-COOH, stability in acid groups is very important and determines the degree of acidity of an organic compound.

Acetic acid is one of the simplest carboxylic acid. Solution of acetic acid in water is a weak acid, meaning that only partially dissociate into H + and CH3COO-. Acetic acid is a chemical reagent and industrial raw materials is important. Pure acetic acid (called glacial acetic acid) is a colorless hygroscopic liquid, and has a freezing point of 16.7 ° C.

Acidity of Organic Acid

 Why organic acids acidic?

Organic acids as weak acids

simple acid release hydrogen ions to water molecules when they dissolve in water.

Acid in solution has the following equilibrium:

 
An atom hidroksinium formed together with the anion (negative ion) from the acid.
This equation is sometimes simplified by eliminating water to emphasize the ionization of the acid.













   The purpose of the organic acid is a weak acid is very incomplete because of ionization. At one time most of the acid in solution as molecules that are not ionized. For example, in the case etanoik acid, a solution containing 99% etanoik acid molecules and only 1 percent of that is really ionized. The position of the equilibrium being shifted to the left.
Comparing the strength of a weak acid
The strength of weak acids measured by skalapKa. The smaller the stronger the acidity level.
  The difference between the acid strength of carboxylic acids, phenols and alcohols.
Factors to be considered
Two factors that affect the ionization of the acid is:
• The strength of the bond to be decided,
• the stability of the ions formed.
In this case, you break the bond of the same molecule (between O and H) so it can be determined bond strength is the same.
The most important factor in determining the relative strength of the molecule is in the nature of the ions formed.
acid Etanoik
Etanoik acid has the structure:



  Hydrogen is causing the acidic nature of hydrogen bound to oxygen. When etanoik ionized acid formed ethanoate ion, CH3COO-.
In ethanoate ion, one of the free electrons from the negative oxygen are in a state of almost parallel to the p orbitals and the resulting overlap between the other oxygen atom and a carbon atom.
 
So there is delocalised pi system of whole-COO-. Because hydrogen is more electronegative than carbon, so that electron delocalization occurs system longer is in the region of oxygen atoms.
Then where is the negative charge of the whole molecule? Jwabannya is spread among the entire molecule-COO-, but the most likely find it in the Sar between the two oxygen atoms.
The more you spread the load, the more stable the ion. Or in this case, if you mendelokalisasikan negative charge to a few atoms, the charge will be less attracted to the tendency to form hydrogen ions re etanoik acid was reduced.

phenol
Phenol has an-OH group attached to the chain benzennya.

When the hydrogen-oxygen bond in phenol is lost, you get a phenoxide ion, C6H5O-.
Delocalization also occurs in this ion. At this time, one of the free electrons from the oxygen atom overlap with the electrons of the benzene chain.

This resulted dislokalisasi overlap. And as a result of not only the negative charge is on oxygen but scattered throughout the molecule.

In the phenoxide ion, single oxygen atom is still the most electronegative and delocalized system centered on the oxygen region. So that the oxygen atom has a charge of most negative, even though it does not have as much cargo if delocalization does not occur.
Delocalisation makes phenoxide ion is more stable than it should thus becomes acidic phenols. But not divide the charge delocalization effectively. The negative charge around the oxygen will be attracted to the hydrogen ion dam makes it easier phenol formation again. So that phenol acid is very weak.



ethanol
Ethanol, CH3CH2OH, is a very weak acid up to the point that you can think of it not as sour. If the oxygen and hydrogen bonding disconnected and release of ions, ion etokside formed.



 

There is no way to mendelokalisasi negative for a strong bond with the oxygen atom. The negative charge will be very interesting and ethanol hydrogen atoms will be easily reformed.

Organic bases
Why primary amines bases?
  Ammonia is a weak base
Ammonia in solution is in equilibrium as follows.
 
An ammonium ion is formed along with hydroxide ions. Since ammonia is a weak base, the state of the ion is not long and back again to its original state. Equilibrium shifts to the left.
Ammonia acts as a base because the lone pair of active nitrogen, nitrogen is more electronegative than hydrogen so attractive bonding electrons on the ammonia molecule at him. Or in other words the presence of a lone pair going negative charge around the nitrogen atom. The combination of these extra negativity and appeal lone pair, draw hydrogen from water.

  Comparing the strength of the weak base
The strength of a weak base is scaled pKb. The smaller the value of this scale is a stronger base.
  Explain the difference in the base
Things to think about
Two factors that affect the strength of a base is:
• Ease of lone pair binds hydrogen ions,
• the stability of the ions formed.

  Why aliphatic primary Amin is a stronger base than ammonia?
methylamine
Methylamine has the structure:
 
The difference is the presence of ammonia in methyl amine CH3. The alkyl group has a tendency to push the electrons away from them. This will mean that a number of additional negative charge around the nitrogen atom. Additional negative charge is more interesting pairing free hydrogen atom.

The more negative nitrogen bound hydrogen ions more easily.
And what about the methyl ion current is established, whether it is more stable than the ammonium ion?
Methylammonium ions, the positive charge of the ions scattered around effect "electron boost" methyl. The more you spread the charge, the more stable the ion. However, the ammonium ion is no way to spread the positive ions.
Summary:
• Nitrogen is more negative than in the ammonia methylamine, thus binding more active hydrogen.
• Ions are formed in methylamine is more stable than ions formed from ammonia, making it more difficult to change the form of hydrogen ions more ..
Conclusion: methylamine is a stronger base than ammonia.
  Why aromatic primary amines are weaker bases than ammonia?
Aromatic primary amines are compounds in which-NH2 group is attached directly to a benzene ring. That might be you often encounter is phenylamine.
Phenylamine has the structure:

 
Nitrogen lone pair of electrons delocalized ring touching .....

. . . and become delocalized along.

This means that couples no longer fully free to join the hydrogen ions. Nitrogen is still the most electronegative atom in the molecule and therefore approaching the delocalisation going in that direction, but the intensity of the charge around the nitrogen is not such as in within the molecule.

I will give an example of each of the organic acid and an organic base

organic acid
acetic acid
Acetic acid, ethanoic acid or acetic acid is an organic acid chemical compounds known as sour flavoring and aroma in food. Acetic acid has the empirical formula C2H4O2. This formula is often written in the form of CH3-COOH, CH3COOH, or CH3CO2H. Pure acetic acid (called glacial acetic acid) is a colorless hygroscopic liquid, and has a freezing point of 16.7 ° C.
Acetic acid is one of the simplest carboxylic acids, as formic acid. Solution of acetic acid in water is a weak acid, meaning that only partially dissociate into H + and CH3COO-. Acetic acid is a chemical reagent and industrial raw materials is important. Glacial acetic acid is a trivial name that refers to acetic acid which is not mixed with water. So called because water-free acetic acid forms crystals resemble ice at 16.7 ° C, slightly below room temperature.
Chemical properties
Acidity
Hydrogen atoms (H) in the carboxyl group (-COOH) in carboxylic acids such as acetic acid can be released as H + ions (protons), thus giving the acid. Acetic acid is a weak monoprotic acid with a value of pKa = 4.8. Conjugate base is acetate (CH3COO-). A 1.0 M solution of acetic acid (approximately equal to the concentration in the vinegar) has a pH of approximately 2.4.
The crystal structure of acetic acid shows that acetic acid molecules form a dimer pairs are linked by hydrogen bonds. Dimers can also be detected in the steam temperature of 120 ° C. Dimers also occur in an aqueous solution in a solvent non-hydrogen-bonded, and sometimes on pure acetic acid. [4] Dimer destroyed in the presence of hydrogen bonded solvent (eg water) as solvent
Acetic acid solvent protic liquid is hydrophilic (polar), much like water and ethanol. Acetic acid has a dielectric constant of the medium is 6.2, so that it can dissolve both polar compounds and inorganic salts are like sugar and non-polar compounds such as oils and elements such as sulfur and iodine. Acetic acid bercambur easily with polar or nonpolar solvents such as water, chloroform and hexane. Solubility properties and ease of mixing of acetic acid makes it widely used in the chemical industry.

organic base

Ammonia is a chemical compound with the formula NH3. These compounds are usually found in the form of gas with a characteristic pungent odor (called ammonia smell). Ammonia is a compound of nitrogen and most importantly in the production. Although ammonia has a significant contribution to the presence of nutrients in the earth itself is a compound ammonia kausatik and can damage health. Ammonia is an alkaline gas is colorless and has a high irritation power generated during the decomposition of organic material by deamination. Ammonia is toxic to fish. Ammonia is produced from the secretions / fish waste. Ammonia in surface water from the urine and feces, as well as from the oxidation of organic substances (HaObCcNd) in microbiology, which comes from natural water or wastewater industry and residents.
Ammonia synthesis reaction thermochemical equation is: 

N₂(g) + 3H₂(g) ⇄ 2NH₃(g) ∆H = -92,22 Kj Pada 25^oC : Kp = 6,2×105

Table Optimum Preparation Conditions NH3  

No	Factor	Reaction : N2(g) + 3H2(g) ⇄ 2NH3(g) ∆H= -92.22 kJ	Optimum condition
1.	temperature	1. The reaction is exothermic 2. Low temperature will shift the equilibrium to right 3. Constraints: The reaction is slow	400-600oC
2.	presurre	1. Jumlah mol pereaksi lebih besar dibanding dengan jumlah mol produk. 2. Enlarge pressure will shift the equilibrium to right. 3. Constraint system pressure is limited by the ability of tools and safety factors. 150-300 atm	150-300 atm
3.	concentration	Taking NH3 concentration will continually shift the equilibrium towards the right _	_
4.	Catalysts	Catalysts do not shift the equilibrium right, but accelerate the overall rate of the reaction	with a mixture of Al2O3 Fe KOH and other salt

 Ammonia properties include:
1. Ammonia is a colorless gas and it smelled very stimulating so that the gas is easily recognized by their smell.
2. Very easily soluble in water, which is the standard state, 1 liter of water dissolved in 1180 liters of ammonia.
3. Gas is easy to melt, liquid ammonia freezes at-780C and boils at -330 C, have a vapor pressure: 400 mmHg (-45.4 ° C), solubility in water: 31 g/100g (25 ° C), weighed type: 0682 (-33.4 ° C), vapor density: 0.6 (air = 1), the critical temperature: 133oC
4. Ammonia is corrosive to copper and tin.
...