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BEST WAY TO LEARN THE ELEMENTS! - Periodic Table Song

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Alcohols

Origin of the word alcohol:
Of those, ethanol (C₂H₅OH) is the type of alcohol found in alcoholic beverages, and in common speech the word alcohol refers specifically to ethanol.The word alcohol appears in English in the 16th century,  loaned via French from medical Latin, ultimately from the Arabic الكحل (al-kuḥl, "the kohl, a powder used as an eyeliner").The current Arabic name for alcohol is الكحول al-kuḥūl,  re-introduced from western usage.

The general formula of alcohol  is C_nH_2n+1OH. An alcohol is any organic compound in which a hydroxyl functional group  (-OH) is bound to a carbon atom, usually connected to other carbon or hydrogen atoms.

The suffix -ol appears in the IUPAC chemical name of all substances where the hydroxyl group is the functional group with the highest priority.

Common Alcohols :

The most commonly used alcohol is ethanol, C₂H₅OH. Ethanol has been produced and consumed by humans for millennia, in the form of fermented and distilled alcoholic beverages. It is a clear flammable liquid that boils at 78.4 °C, which is used as an industrial solvent, car fuel, and raw material in the chemical industry. Ethanol in this form is known generally as denatured alcohol; when methanol is used, it may be referred to as methylated spirits or "surgical spirits".

The simplest alcohol is methanol, CH₃OH, which was formerly obtained by the distillation of wood and, therefore, is called "wood alcohol". It is a clear liquid resembling ethanol in smell and properties, with a slightly lower boiling point (64.7 °C), and is used mainly as a solvent, fuel, and raw material. Unlike ethanol, methanol is extremely toxic: One sip (as little as 10 ml) can cause permanent blindness by destruction of the optic nerve and 30 ml (one fluid ounce) is potentially fatal.Two other alcohols whose uses are relatively widespread (though not so much as those of methanol and ethanol) are propanol and butanol. Like ethanol, they can be produced by fermentation processes.

Etymology:

Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable hydrocarbons and ethers. The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon Hexane (a common constituent of gasoline), and 34.6 °C for Diethyl ether.
Alcohols, like water, can show either acidic or basic properties at the O-H group. With a pK_a of around 16-19, they are, in general, slightly weaker acids than water, but they are still able to react with strong bases such as sodium hydride or reactive metals such as sodium. The salts that result are called alkoxides, with the general formula RO^- M⁺.
Meanwhile, the oxygen atom has lone pairs of nonbonded electrons that render it weakly basic in the presence of strong acids such as sulfuric acid. Mild oxidation in the presence of oxygen gives the products below : 

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Aspirin

Turns to be the Century Miracle Drug!

Aspirin Description:

Aspirin belongs to a group of drugs called Salicylates. Other members of this group include Sodium Salicylate, Choline Salicylate, and Magnesium Salicylate. These drugs are more expensive and no more effective than aspirin. However, they are a little easier on the stomach. Aspirin is quickly absorbed into the bloodstream and provides quick and relatively long-lasting pain relief. Aspirin also reduces inflammation. Researchers believe these effects come about because aspirin blocks the production of pain-producing chemicals called prostaglandins. According to the theory concerning the origin of the name aspirin, it comes from the combination of acetyl; the Latin Spiraea, the genus of plants to which meadowsweet belongs and which also contains salicylic aldehyde, a precursor to salicylic acid (in German );salicylic acid is Spirsäure.

Uses of Aspirin:

Aspirin is used to relieve many kinds of minor aches and pains--headaches, toothaches , muscle pain, menstrual cramps, the joint pain from arthritis, and aches associated with colds and flu. Some people take aspirin daily to reduce the risk of stroke, heart attack, or other heart problems. Many other over-the-counter medicine contain Aspirin. Alka-Seltzer Original Effervescent Antacid Pain Reliever, for example, contains aspirin for pain relief and sodium bicarbonate to relieve acid indigestion, heartburn, and sour stomach.
Aspirin, also known as 'acetylsalicylic acid', has a chemical formula of C9H8O4.

The chemical structure of aspirin:

Aspirin is prepared  salicyilic acid according to the reaction below :

Acid Rain

Rain is indespensible for life on Earth.Unpolluted rain is normally slightly acidic, with a pH of 5.6. Carbon dioxide (CO₂) from the atmosphere dissolves   in water to form carbonic acid.

However , pollutants  like sulfur and nitrogen oxides   combine  with the rain, the acidity of rain  increases greatly. These gases are oxidized in the air before been  captured by raindrops to form nitric and sulfuric acids  .  We commonly know this as acid rain, but we can have acidic snow or hail and even acidic dust particles falling from the sky.

  

Acid rain is a human-related phenomena. Since our industries are so fond of burning fossil fuels (coal and oil) they tend to release a lot of sulfur into the air. This sulfur combines with the oxygen already present in the air to form sulfur dioxide (SO₂).

Also, since we like to drive big fancy cars rather than ride bikes or walk, we cause the formation of nitrogen oxides (NO or NO₂ or NO ₃, etc) in air from burning gasoline.

CHEMICAL REACTIONS:

Formation of SO₂ and nitrogen oxides (NO & NO_x):

S(in fuel) + O₂ -------> SO₂
N₂ + O₂ -------> 2NO
NO + .5O₂ -----> NO₂
Formation of hydrogen peroxide

VOC + sunlight + HO₂ (in air) -------> H₂O₂
***VOC = Volatile Organic Compound ***
Formation of acids :

SO₂ + H₂O₂ and O₃ (in clouds) -------> H₂SO₄ SO₂+ OH + O₂ (in air) --------------> H₂SO₄
SO₂ + Oxidants (from wet surfaces) --> H₂SO₄ 
NO_x + sunlight + OH (air) ------------> HNO₃

EFFECTS OF ACID RAIN

 

 
 The acids can cause a lot of harm to things that we care about and enjoy. For example. some animals, like frogs and fish, have difficult time adapting to and reproducing in an acidic environment.

 Also, the leaves of many plants and trees can be severely damaged by acidic precipitation. It is believed that acid rain leaches calcium and magnesium from the soil. This causes a decrease in  the ratio of calcium to aluminum in the soil, which stimulates the uptake of aluminum by roots. The uptake of aluminum by trees and plants can be destructive. Finally, in cites and towns all over the world, stone structures, such as buildings, ancient ruins, etc are being deteriorated by the corrosive effects of acidic rainfall.

Autoionozation of water for Grade 10

The self-ionization of water (also autoionization of water, and autodissociation of water) is the chemical reaction in which a proton is transferred from one water molecule to another, in pure water or an aqueous solution, to create the two ions, hydronium, H₃O⁺ and hydroxide, OH⁻.




Chemically pure water has an electrical conductivity of 0.055 µS·cm⁻¹. According to the theories of Svante Arrhenius, this must be due to the presence of ions. The ions are produced by the self-ionization reaction

H₂O + H₂O H₃O⁺ + OH⁻

This equilibrium applies to pure water and any aqueous solution.

The value of K_w decreases as temperature increases and it decreases with increasing pressure.

The equilibirum expression for the above reaction is written below and is treated mathematically like all equilibrium expressions.

K_w = [H₃O⁺][OH^-]
At 25^oC, the value of K_w has been determined to be 1 x 10^-14. 

If one knows the concentration of either the hydronium ions or of the hydroxide ions in a water solution,. the other ion concentration can be determined.

Example:  What is the hydronium ion concentration in a water solution that is 0.050 M NaOH?
The NaOH is a strong base and will 100% dissociate into its component ions.  Therefore, the concentration of the hydroxide ions will be 0.050 M.  The hydronium ion concentration is then calculated.

[H₃O⁺] = (1 x 10^-14)/(0.050) = 2.0 x 10^-13 M
Example:  What is the hydroxide ion concentration in a water solution that is 4.0 x 10^-5 M H₃O⁺?

[OH^-] = (1 x 10^-14)/(4.0 x 10^-5) = 2.5 x 10^-10 M .

Ozone Depletion

Take care of our planet:

Ozone (O3) is found in two different parts of our atmosphere. Ground level ozone, a human health irritant and component of smog, is found in the lower atmosphere (troposphere) and has nothing to do with the "ozone hole." However, ozone in the stratosphere—the layer of atmosphere above the troposphere _ accounts for the vast majority of atmospheric ozone. Stratospheric ozone is protective for human health as it absorbs ultraviolet radiation from the sun, preventing the radiation from hitting Earth's surface and harming living organisms from this biologically dangerous radiation.




The stratospheric ozone layer shields life on Earth from the Sun’s harmful ultraviolet radiation. Chemicals that destroy ozone are formed by industrial and natural processes. With the exception of volcanic injection and aircraft exhaust, these chemicals are carried up into the stratosphere by strong upward-moving air currents in the tropics. Methane (CH₄), chlorofluorocarbons (CFCs), nitrous oxide (N₂O) and water are injected into the stratosphere through towering tropical cumulus clouds. These compounds are broken down by the ultraviolet radiation in the stratosphere. Byproducts of the breakdown of these chemicals form “radicals”—such as nitrogen dioxide (NO₂) and chlorine monoxide (ClO)—that play an active role in ozone destruction. Aerosols and clouds can accelerate ozone loss through reactions on cloud surfaces. Thus, volcanic clouds and polar stratospheric clouds can indirectly contribute to ozone loss.


 

(CFCs, freons, halons.) CFCs and other contributory substances are referred to as ozone-depleting substances (ODS).

Since the ozone layer prevents most harmful UVB wavelengths (280–315 nm) of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocol that bans the production of CFCs, halogens  and other ozone-depleting chemicals such as carbon tetrachloride and trichloroethane. It is suspected that a variety of biological consequences such as increases in skin cancer, cataracts, damage to plants, and reduction of plankton populations in the ocean's photic zone may result from the increased UV exposure due to ozone depletion.




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