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Showing posts with label Chemistry in Daily Life. Show all posts
Showing posts with label Chemistry in Daily Life. Show all posts

Thursday, September 8, 2011

chemical reaction and equation: Why do fire flies glow at night?


1. A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed. Write the chemical reaction involved and also mention the type of the chemical reaction?
Answer:  KCl (aq) + AgNO3 (aq) AgCl (s) + KNO3 (aq)
It is a double displacement and precipitation reaction.
2. Ferrous sulphate decomposes with the evolution of a gas having a characteristic odour of burning sulphur. Write the chemical reaction involved and identify the type of reaction.
Answer:  2FeSO4(s) --H---e---at Fe2O3(s) + SO2(g) + SO3(g)
It is a thermal decomposition reaction
3. Why do fire flies glow at night?
Answer: Fire flies have a protein which in the presence of an enzyme undergoes aerial oxidation. This is a chemical reaction which involves emission of visible light. Therefore, fire flies glow at night.
4. Grapes hanging on the plant do not ferment but after being plucked from the plant can be fermented. Under what conditions do these grapes ferment? Is it a chemical or a physical change?
Answer: Grapes when attached to the plants are living and therefore their own immune system prevents fermentation. The microbes can grow in the plucked grapes and under anaerobic conditions these can be fermented. This is a chemical change.
5. Which among the following are physical or chemical changes?
(a) Evaporation of petrol 
(b) Burning of Liquefied Petroleum Gas (LPG)
(c) Heating of an iron rod to red hot.
(d) Curdling of milk
(e) Sublimation of solid ammonium chloride
Answer:  (a), (c) and (e) — are physical changes. 
(b) and (d) are chemical changes
6. During the reaction of some metals with dilute hydrochloric acid, following observations were made.
(a) Silver metal does not show any change
(b) The temperature of the reaction mixture rises when aluminium (Al) is added.
(c) The reaction of sodium metal is found to be highly explosive
(d) Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.  
Explain these observations giving suitable reasons.
Answer:(a) Silver metal does not react with dilute HCl
(b) The temperature of the reaction mixture rises when aluminium is added because it is an exothermic reaction.
(c) Reaction of sodium metal is found to be highly explosive because it is an exothermic reaction
(d) When lead is treated with hydrochloric acid, bubbles of hydrogen gas are evolved
                  Pb + 2HCl PbCl2 + H2
6. A substance X, which is an oxide of a group 2 element, is used intensively in the cement industry. This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the chemical reactions involved.
Answer: Calcium oxide CaO(s) + H2O(l) Ca(OH)2(aq)
7. Write a balanced chemical equation for each of the following reactions and also classify them.
(a) Lead acetate solution is treated with dilute hydrochloric acid to form lead chloride and acetic acid solution.
(b) A piece of sodium metal is added to absolute ethanol to form sodium ethoxide and hydrogen gas.
(c) Iron (III) oxide on heating with carbon monoxide gas reacts to form solid iron and liberates carbon dioxide gas.
(d) Hydrogen sulphide gas reacts with oxygen gas to form solid sulphur and liquid water.
Answer:(a) Pb(CH3COO)2 + 2HCl PbCl2 + CH3COOH
 Double displacement reaction
(b) 2Na + 2C2H5OH 2C2H5ONa + H2
 Displacement reaction
(c) Fe2O3 + 3CO 2Fe + 3CO2
 Redox reaction
(d) 2H2S + O2 2S + 2H2O
 Redox reaction
8. Why do we store silver chloride in dark coloured bottles?
Answer:  Silver chloride on exposure to sunlight may decompose as per the following reaction.
2AgCl 2Ag + Cl2 Therefore, it is stored in dark coloured bottles.
9.Take about 2 g barium hydroxide in a test tube. Add 1 g of ammonium chloride and mix with the help of a glass rod. Touch the bottom of the test tube with your palm. What do you feel? Is this an exothermic or endothermic reaction?
Answer:  Ba(OH)2 +2NH4 Cl ----------------à BaCl2 + 2NH4(OH)      Endothermic reaction
10. What is the difference between the displacement and double displacement reactions? Write equations for these reactions.  
Answer: In displacement reaction, one element from its salt is displaced by a more reactive element e.g. in following example, Cu is displaced by Zn from CuSO4 because Zn is more reactive.
CuSO4 + Zn ---> ZnSO4 + Cu  
Also, Zn(s) + CuSO4 (aq) ZnSO4 (aq) + Cu(s) ;   Pb(s) + CuCl2(aq) PbCl2(aq) + Cu(s)
Zinc and lead are more reactive elements than copper. They displace copper from its compounds
In double displacement reaction, exchange of ions takes place between two reactants to form new products.
Na2SO4 + BaCl2 ---> BaSO4 + 2NaCl
Here, the white precipitate of BaSO4 is formed by the reaction of SO4-2 and Ba2+               

Saturday, July 2, 2011

Salt - The Spice of Life

Salt - The Spice of Life: For every meal there is one thing people generally reach for before they even take a bite – the salt shaker. Salt is one of the oldest spices used and is a key component to humans, animals, and plants.

Its flavor is unique and versatile, salt has been a staple throughout time. Enhancing almost every dish, salt is added to breads, meats, fruits and vegetables to sauces and desserts.

Additionally, salt aids foods in a variety of ways like:

Preservation – helps protect against microorganisms, bacteria through dehydration and preventing growth of bacteria, which slows or prevents spoilage.

Texture Aid – in bread making, allows the dough to rise by giving helping the gluten hold more water and carbon dioxide. In meats it improves tenderness and in cheeses it aids in consistency of the cheese and the hardness of the rind.

Binder – in processed meats it helps retain water which reduces the loss of meat when cooking.

Color Developer – in ham, bacon, and other processed meats it helps obtain the desired color. It also helps create a golden crust for breads.

Fermentation Control – slows and controls the fermentation process in:

Pickling
Cheese production Sauerkraut production Summer sausage production

Friday, July 1, 2011

Why aqueous solution of sodium carbonate is basic in nature?

Question: Why aqueous solution of sodium carbonate is basic in nature?


Answer: Sodium bicarbonate is an amphoteric compound. Aqueous solutions are mildly alkaline due to the formation of carbonic acid and hydroxide ion:
NaHCO− 3 + H2O → H2CO3 + OH−  
Question: Why is an aqueous solution of ammonium chloride acidic in nature?
Answer: A basic component is the one that produces hydroxide (OH-) ions when dissolved in water. In aqueous solution of ammonium chloride, ammonium ions (NH4+) first associate with H2O and form ammonia and hydroxide ions.
NH4Cl + H2O = NH4+ + HCl ( equation 1)
NH4+ + H2O = NH3 + OH- (equation 3)
Since ammonium ions produce hydroxide ions, NH4+ are considered to be the basic components.
For more Questions: Visit: www.jsuniltutorial.weebly.com/ 
and:
http://chemistryadda.blogspot.in/2011/06/extrascore-science-acid-base-and-salt.html

Why are commercial samples of bleaching powder not completely soluble in water?

Why are commercial samples of bleaching powder not completely soluble in water?


Because it is essentially chlorinated CaO, which is insoluble. It releases chlorine on adding to water. Stable bleaching powder has about 37% available chlorine when fresh.



Why aqueous solution of sodium carbonate is basic in nature?


Friday, June 10, 2011

Solved example for 10th class Science Acid , Base and salt

1. A milkman adds a very small amount of baking soda to fresh milk

Ans: A milkman adds a very small amount of baking soda to fresh milk to increase alkalinity of milk that prevent to set as curd

2. Why do acids not show acidic behaviour in the absence of water?

Answer : In absence of water, acids do not dissociate H - So, they do not show acidic behaviour.

3. Alcohols and Glucose contain hydrogen but are not categorized as acids.

Answer: Alcohols and Glucose does not dissociate into ions on dissociation. So, the are not an acid.

4. Plaster of Paris should be stored in a moisture-proof container. Explain why?

Answer : Plaster of Paris easily absorbs water and forms hard gypsum. Thus, if Plaster of Paris is not kept in a moisture-proof container, then all Plaster of Paris will get converted into gypsum.

Ca SO4 .1/2 H2O + 3/2 H2O ------> CaSO4 . 2H2O ( gypsum)

5. Why is calcium sulphate hemihydrates called 'Plaster of Paris'?

Answer: A big source of this substance is at Montmartre in Paris. So it is called as Plaster of Paris.

6. Equal lengths of the magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH3COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why?

Answer : Since HCl is strong acid and CH3COOH is a weak acid so being HCl a strong acid , dissociate more so that In test tube A, fizzing occur more vigorously.

7. Name a solution reacts with crushed egg-shells to give a gas that lime-water milky.


Answer H Cl , H Cl + CaCO3 ----> CaCl2 + Co2 + H2O

In this reaction carbon di oxide is given off that tumn lime water milky

8. Why does distilled water not conduct electricity, whereas rain water does.

Answer : Distilled water does not dissociate into ions. So it doe snot conduct electricity. Rain water has dissolved CO2 in it which form carbonic acid.

CO2 + H2O ----> H2CO3 This carbonic acid dissociate into ions.

H2CO3 + 2H2O-------à (H3O+)2 + CO3-2

These ions are responsible for electrical conductivity of rain water.

9. What is aqua-regia ?

Answer : A mixture (acid) of HCl and HNO3. Formed by mixing 3 moles of HCl and 1 mole of HNO3 i.e in the ratio 3:1.

This is one of the few acids that can dissolve metals like gold and platinum and use by gold smith . FIrst discovered by the famous muslim scientist Jabir-bin-Haiyan(known as the father of chemistry). It is a highly-corrosive fuming yellow liquid.

The name "Aqua Regia" is latin for "Royal Water". It was so named because it could dissolve the royal noble metals.Aqua regia works to dissolve gold, even though neither constituent acid will do so alone because, in combination, each acid performs a different task. Nitric acid is a powerful oxidizer, which will actually dissolve a tiny (virtually undetectable) amount of gold, forming gold ions.

 The hydrochloric acid provides a ready supply of chloride ions, which react with the latter, thus taking the gold out of the solution. This allows further oxidation of gold to take place, and so the gold is dissolved.

10. Name the sodium compound which is used for softening hard water.

Answer : Hard water is water that has high mineral content .Hard water has high concentrations of Ca2+ and Mg2+ ions. Washing soda i.e., sodium carbonate (Na2CO3). is used for softening hard water.

It precipitates calcium and magnesium ions out of hard water.

11. Why should curd and sour substances not be kept in brass and copper vessels?

Answer : Curd and sour substances contain acids. Acids reacts with metals to give salt and hydrogen gas. So, if such substances are kept in copper container, the acid will react and the container will be corroded.

12. What is efflorescence?

Answer: Efflorescence is the loss of water (usually as evaporation to air) in an aqueous solution of salts, leaving behind crusts of solid salt crystals, called efflorescent salts

13.Explain the term olfactory indicator.

Ans. Substances whose odour changes in acidic or basic medium are called olfactory indicator. e.g. Eucalyptus (nilgiri) Oil, Onion & clove extract.










14. What is universal indicator? Does  Mg(OH)2  react with sodium hydroxide? If not, why?

Ans. Universal indicator is a mixture of several indicators which gives different colours at different pH values of the pH scale.

Mg(OH)2 does not react with sodium hydroxide as both are bases having the same negative radical i.e. OH-

15.Why is Plaster of Paris written as CaSO4. ½ H2O ? How is it possible to have half a water
molecule attached to CuSO4? 

Ans. The actual formula of Plaster of Paris is 2CaSO4.H2O which means that one molecule of
H2O is associated with two molecules of CaSO4. The formula for simplicity is written as CaSO4.
½H2O.

Picture

Friday, May 20, 2011

Class X Chemical properties of Metal and Nonmetal

Metals are Electropositive Elements
Metals are very reactive. Metals tend to loose electrons easily and form positively charged ions; therefore metals are called electropositive elements. Sodium metal forms sodium ions Na+, Mg forms positively charged Magnesium ions Mg2+and aluminium forms aluminium ions Al3+. The electropositive nature allows metals to form compounds with other elements easily.
Na    -----------à       Na+ + e-
(2, 8, 1)                 ( 2, 8)
Mg ---------------àMg2+ + 2e-
(2, 8, 2)             (2, 8)
Al   --------------- Al3+ + 3e-
(2, 8, 3)            (2, 8)
Reaction of Metals with Oxygen
Metals like sodium (Na) and potassium (K) are some of the most reactive metals. Potassium, sodium, lithium, calcium and magnesium react with oxygen and burn in air.
Metals from aluminium to copper in the activity series of metals, react slowly when heated in air to form the metal oxides. Aluminium is the fastest and copper is the slowest of them.
Sodium metal reacts with the oxygen of the air at room temperature to form sodium oxide. Hence, sodium is stored under kerosene to prevent its reaction with oxygen, moisture and carbon dioxide.

Sodium oxide is a basic oxide which reacts with water to form sodium hydroxide.

Mg does not react with oxygen at room temperature. On heating, Mg burns in air with intense light and heat to form MgO.
2Mg (s) + O2 (g) ---Heat------à 2 MgO(s)
Zinc metal burns in air only on strong heating to form zinc oxide.
2Zn (s) + O2 (g) ---Heat------à 2 ZnO(s)
Iron metal does not burn in dry air even on strong heating. In moist air, iron is oxidized to give rust.

On heating in air it burns with a brilliant flame forming triferric tetroxide

Copper is the least reactive metal and does not burn in air even on heating. However, on prolonged strong heating copper reacts with oxygen and forms copper (II) oxide (CuO) outside and copper (I) oxide (Cu2O) inside.

Gold and platinum do not react with oxygen in air.
Reaction of Metals with Water
Potassium, sodium, lithium and calcium react with cold water.
Sodium reacts vigorously with cold water forming sodium hydroxide and hydrogen.

Metals from magnesium to iron in the activity series of metals, react with steam (but not H2O) to form the metal oxide and hydrogen gas.



Red hot iron reacts with steam to form Iron (II, III) oxide.

Note: The reaction between iron and steam is irreversible. Tin, lead, copper, silver, gold and platinum do not react with water or steam.
Reaction of Metals with Acids
Potassium, sodium, lithium and calcium react violently with dilute H2SO4 and dilute HCl, forming the metal salt (either sulphate or chloride) and hydrogen gas. The reaction is similar to the reaction with water.

Magnesium, aluminium, zinc, iron, tin and lead react safely with dilute acid. Magnesium is the fastest and lead is the slowest of the six.


Zinc with dilute sulphuric acid is often used for the laboratory preparation of hydrogen. The reaction is slow at room temperature, but its rate can be increased by the addition of a little copper (II) sulphate. Zinc displaces copper metal, which acts as a catalyst.
Metals below hydrogen (copper, silver, gold and platinum), will not react with dilute acid. They cannot displace hydrogen from the non-metal anion.
Note:  Copper reacts with oxyacids like nitric acid and sulphuric acid because these acids are strong oxidizing agents.
In general,  Hydrochloric acid makes a metal chloride.   
Sulphuric acid makes a metal sulphate.
Reactions with nitric acid are more complex, the nitrate is formed but the gas is rarely hydrogen, and more often, an oxide of nitrogen.
Reaction of Metals with Salt Solutions
Reactive metals can displace any metal less reactive than itself, from the oxide, chloride or sulphate of the less reactive metal in solution or their molten state. If metal A displaces metal B from its solution, it is more reactive than B.
Copper (II) sulphate solution is blue; iron sulphate solution is almost colourless when dilute. 
During the displacement, the blue solution loses its colour and the iron metal is seen to turn pink-brown as the displaced copper becomes deposited on it.
On heating the mixture of magnesium powder and black copper (II) oxide, white magnesium oxide is formed with brown bits of copper


Adding magnesium to blue copper (II) sulphate solution, the blue colour fades as colourless magnesium sulphate is formed and brown bits of copper metal form a precipitate

Monday, May 16, 2011

Chemistry Adda: The Chemistry of Love

The Chemistry of Love - Part 1 
Is there real chemistry behind love? This article is divided in two parts.
Answering the question of last week, yes, there's a lot of real chemistry behind love! Chemistry is in the roots of every step in a relationship, and this field is under continuous research. When you fall in love, your brain suffers some changes and also certain chemical compounds are released. Researchers consider three stages in love: lust, attraction and attachment, each of them involve different chemicals (don't worry about the chemical names, simply get the essence!):
1) Lust
Lust is driven by initial physical attraction and flirting. This stage can depend on characteristics such as a symmetrical face and proportionate body dimensions. Flirting can include gazing into the eyes, touching, and mirroring in body language. The two chemicals that surface during this stage are the sex hormones (testosterone and estrogen) and pheromones.
=>In the animal world, PHEROMONES are individual scent "prints" found in urine or sweat that dictate sexual behavior and attract the opposite sex. The existence of human pheromones was discovered in 1986, finding these chemicals in human sweat.
2) Falling in love - Attraction
When you fall in love you may have many physical symptoms: lose of appetite, can't sleep, can't concentrate, palms sweat, butterflies in stomach... This is due to surging brain chemicals called monoamines:
=> DOPAMINE: it's commonly associated with the pleasure system of the brain, providing feelings of enjoyment and reinforcement to motivate us to do certain activities. It's released by naturally-rewarding experiences, such as sex or food. Some research studies show that when female rodents were injected dopamine in the presence of a male rodent, the female will pick him out of a crowd later.- PHENYLETHYLAMINE: It's a natural amphetamine like the known drug and can cause the same stimulation effects. It contributes to that on-top-of-the-world feeling that attraction can bring, and gives you the energy to stay up day and night with a new love.
- SEROTONIN: it controls impulses, unruly passions, obsessive behavior, aiding the sense of "being in control".
- NOREPINEPHRINE is another neurotransmitter which induces euphoria in your brain, exciting the body by giving it a booster dose of natural adrenaline. This causes the heart to beat faster and blood pressure to rise. That's why you can experience a pounding heart or sweaty palms when you see someone you're attracted to.
3) Attachment - Staying together
There is a sense of calm and stability that we feel with a long-term partner, a sort of bond that keeps couples together. This kind of love is driven these hormones:
- OXYTOCIN: it's sometimes known as "the cuddle chemical." It's the hormone best known for its role in inducing labor by stimulating contractions. But recently it has been observed that it may influence our ability to bond with others, as both genders release this hormone when touching and cuddling, with the oxytocin level peaking during orgasm.
- VASOPRESSIN: also called as "the monogamy chemical". Researchers have found that suppression of vasopressin can cause males to abandon their love nest and seek new mates.
- ENDORPHINS: they are biochemical compounds that enhance our immune system, block the lesion of blood vessel, have anti-aging, anti-stress and pain-relieving effect, and also help to improve your memory.
High levels of oxytocin and vasopressin may interfere with dopamine and norepinephrine pathways, which may explain why with the time attachment grows as mad passionate love fades.
Well, as you can see, there is real chemistry taking place in our body when we are in love! This doesn't mean that love is only chemistry, but at least now you can understand this feeling from a different point of view, don't you

What is cholesterol?

   What is cholesterol? 

"Bad cholesterol" and "good cholesterol"... what's that?


Cholesterol is a fatty substance found in the blood of humans and also in the outer lining of cells (membrane) in the body of animals. The cholesterol that we have in our blood comes from two different sources:
- liver production
- diet: meat, fish, dairy products


After a meal, cholesterol is absorbed by the intestines, goes into the blood and then it's packeged inside a protein coat. These proteins are removed then by the liver.

When you go to the doctor, you are suggested to keep the "bad cholesterol" in blood low and the "good cholesterol" high. Ok. What does this mean?

Bad cholesterol or LDL-low-density lipoprotein: These proteins deposit cholesterol on the artery walls, causing the formation of a hard substance named "cholesterol plaque". With the time, this plaque leds to narrowing of the arteries in a process called atherosclerosis. Because of this, the arteries can get blocked, so LDL is associated with a higher riks of coronary heart diseases.



When the liver has many LDL receptors, this helps to remove more rapidly the LDL cholesterol from the blood, helping to keep the bad cholesterol levels low. The number of LDL receptors depends on both heredity and diet. For instance, people with familial hypercholesterolemia have a very low number of LDL receptors, so they usually have high levels of bad cholesterol. Besides, the bad cholesterol level can raise with diets high in saturated fats (certain vegetable oils and products derived mainly from meat and dairy products).

Good cholesterol or HDL-high-density lipoprotein: These particles extract cholesterol from the artery walls and dispose them through the liver. So they prevent atherosclerosis.

Life style factors and other conditions influence HDL cholesterol levels. HDL cholesterol levels are for instance lower in smokers, people who eat a lot of sweets, and also in those who are overweight and inactive. On the other hand, estrogen increases the HDL cholesterol level, so usually women have higher good cholesterol levels than men.

These are some websites with interesting suggestions to keep your cholesterol at healthy levels:
- Low cholesterol diet.
- Cholesterol Lowdown.

Why smoking is so harmful? 


The word "tobacco" is thought to derive from the Native American word "tabago," for a Y-shaped pipe used in sniffing tobacco powder. Cigarettes and other forms of tobacco consist of dried tobacco leaves, and other ingredients added for flavor and other properties.

Some facts related with smoking:
- Smoking is the second major cause of death in the world. It's responsible for the death of one in ten adults worldwide.
- Smoking accounts for about 80-90% of all chronic obstructive pulmonary disease.
- Smoking is involved in 85% of all lung cancer deaths.
- Smoking is the major cause of cancer of the lips, tongue, mouth, pharynx, larynx and esophagus.
- Smoking has many other harmful effects in the body, a too long list to include it here.

Why smoking causes cancer? It's because tobacco and tobacco smoke contain more than 60 carcinogenic compounds. In general, more than 4,000 individual substances have been identified in tobacco smoke, including carbon monoxide, hydrogen cyanide, ammonia and other toxic irritants.

Besides all the harmful effects of tobacco, it's addictive, and this explains why although 70% of smokers want to quit and 35% attempt to quit each year, fewer than 7% succeed. The main reason why tobacco becomes addictive is due to its content of nicotine, which alters brain functioning.

Nicotine is a naturally occurring liquid alkaloid. An alkaloid is an organic compound made out of carbon, hydrogen, nitrogen and sometimes oxygen. These chemicals have potent effects on the human body. For example, many people enjoy the stimulating effects of another alkaloid, caffeine.
Nicotine:

When you smoke, nicotine is absorbed through the skin and mucosal lining of the mouth and nose or by inhalation in the lungs. Once in the body, it activates the same reward system as do other drugs such as cocaine or amphetamine, although to a lesser degree. In the brain, nicotine increases the level of the neurotransmitter dopamine, which is a chemical in the brain responsible for feelings of pleasure. The acute effects of nicotine subside within minutes, so people continue dosing themselves frequently throughout the day to maintain the pleasurable effects of nicotine and to prevent withdrawal symptoms.

Why do onions make you cry?

Chemistry Adda  >>>>>  Why do onions make you cry? 

Who has never cried while cutting an onion? (well, apart from those who have never cut one hehehe). This is a little explanation in easy terms.
Inside the onion cells there are some chemical compounds that contain sulfur. When you cut an onion its cells are broken and those chemical compounds then undergo a reaction that transforms them into a more volatile sulfured products, which are released into the air.
These sulfured compounds react with the moisture in your eyes forming sulfuric acid, which produces a burning sensation. The nerve endings in your eyes are very sensitive and so they pick up on this irritation. The brain reacts by telling your tear ducts to produce more water, to dilute the irritating acid. So you cry to keep your eyes protected from the acid.
There are some tricks to make onion-dicing less problematic:
Chop the onion under cold water. The volatile sulfured compounds will be released but then they react with the water, instead of reaching your eyes.
You can freeze the onion for 10 minutes before cutting it. The cold temperature of the onion will slow down the chemical reaction which forms the volatile sulfured compunds.

Chemistry Adda: Why meals are cooked faster in a pressure cooker?

Chemistry Adda

Why meals are cooked faster in a pressure cooker? 

A pressure cooker is like any other pot but with a more elaborated lid that seals the pot completely. When you heat water inside the pot it boils and the steam cannot escape, so it remains inside and starts to build up pressure. Under pressure, cooking temperatures raise much higher than under normal conditions (higher than the boiling point of water, that is 100ºC), so then the food is cooked much faster. Cooking times can be reduced by a factor of three or four.

Besides cooking faster, this method retains more nutrients present in the food than other methods. And did you know that a pressure cooker is often used by mountain climbers? Without it, water boils off before reaching 100ºC because of the lower atmospheric pressure at high altitudes, leaving the food improperly cooked.

Chemistry Adda : Chemistry inDaily Life

Chemistry Adda Chemistry in Daily Life
Soap is formed by molecules with a "head" which likes water (hydrophilic) and a long chain which hates it (hydrophobic).



Because of this dualism, soap molecules act like a diplomat, improving the relationship between water and oil. How? When soap is added to the water, the hydrophilic heads of its molecules stay into the water (they like it!), while the long hydrophobic chains join the oil particles and remain inwards (escaping from the water). In that way, they form circular groups named micellas, with the oily material absorbed inside and trapped.



An emulsion of oil in water is then formed, this means that the oil particles become suspended and dispersed into the water. Thus, those oil particles are liberated from the cloth or the skin, and the emulsion is taken away with the rinsing.
In summary, soap cleans by acting as an emulsifier. It allows oil and water to mix so that oily grime can be removed during rinsing.There are more things involved in this process, such as for instance changes in the superficial tension of water, but this is the general idea.
Soap is formed by molecules with a "head" which likes water (hydrophilic) and a long chain which hates it (hydrophobic).


Because of this dualism, soap molecules act like a diplomat, improving the relationship between water and oil. How? When soap is added to the water, the hydrophilic heads of its molecules stay into the water (they like it!), while the long hydrophobic chains join the oil particles and remain inwards (escaping from the water). In that way, they form circular groups named micellas, with the oily material absorbed inside and trapped.



An emulsion of oil in water is then formed, this means that the oil particles become suspended and dispersed into the water. Thus, those oil particles are liberated from the cloth or the skin, and the emulsion is taken away with the rinsing.
In summary, soap cleans by acting as an emulsifier. It allows oil and water to mix so that oily grime can be removed during rinsing.There are more things involved in this process, such as for instance changes in the superficial tension of water, but this is the general idea.

Because of this dualism, soap molecules act like a diplomat, improving the relationship between water and oil. How? When soap is added to the water, the hydrophilic heads of its molecules stay into the water (they like it!), while the long hydrophobic chains join the oil particles and remain inwards (escaping from the water). In that way, they form circular groups named micellas, with the oily material absorbed inside and trapped.



An emulsion of oil in water is then formed, this means that the oil particles become suspended and dispersed into the water. Thus, those oil particles are liberated from the cloth or the skin, and the emulsion is taken away with the rinsing.
In summary, soap cleans by acting as an emulsifier. It allows oil and water to mix so that oily grime can be removed during rinsing.There are more things involved in this process, such as for instance changes in the superficial tension of water, but this is the general idea.
Because of this dualism, soap molecules act like a diplomat, improving the relationship between water and oil. How? When soap is added to the water, the hydrophilic heads of its molecules stay into the water (they like it!), while the long hydrophobic chains join the oil particles and remain inwards (escaping from the water). In that way, they form circular groups named micellas, with the oily material absorbed inside and trapped.


An emulsion of oil in water is then formed, this means that the oil particles become suspended and dispersed into the water. Thus, those oil particles are liberated from the cloth or the skin, and the emulsion is taken away with the rinsing.
In summary, soap cleans by acting as an emulsifier. It allows oil and water to mix so that oily grime can be removed during rinsing.There are more things involved in this process, such as for instance changes in the superficial tension of water, but this is the general idea.

An emulsion of oil in water is then formed, this means that the oil particles become suspended and dispersed into the water. Thus, those oil particles are liberated from the cloth or the skin, and the emulsion is taken away with the rinsing.
In summary, soap cleans by acting as an emulsifier. It allows oil and water to mix so that oily grime can be removed during rinsing.There are more things involved in this process, such as for instance changes in the superficial tension of water, but this is the general idea.
An emulsion of oil in water is then formed, this means that the oil particles become suspended and dispersed into the water. Thus, those oil particles are liberated from the cloth or the skin, and the emulsion is taken away with the rinsing.
In summary, soap cleans by acting as an emulsifier. It allows oil and water to mix so that oily grime can be removed during rinsing.There are more things involved in this process, such as for instance changes in the superficial tension of water, but this is the general idea.
The chromophore is formed by a sequence of linear carbon-carbon double bonds(represented as C=C), much stronger than simple bonds (represented as C-C), so the atoms remain closer to each other. In general, it's necessary at least seven linear conjugated doublebonds for a carotenoid to produce a colour. Besides, the bigger the number of bondsconjugated, the bigger the wavelength of the light absorbed and also the more red the vegetable, as you can see in this picture of the light spectrum:

The tomato is red because of the carotenoid lycopene, which contains 11 conjugated carbon-carbon double bonds. You can count these bonds in the picture below, they are selected in red (the atom carbons are omitted, only the bonds are shown). This compound is generated by the plant to protect itself from the air oxidation. So it's a good antioxidant useful for us too, protecting our cells against the action of free radicals (potent oxidants), which are one of the main responsibles of cardiovascular diseases, cancer and aging.


The tomato is red because of the carotenoid lycopene, which contains 11 conjugated carbon-carbon double bonds. You can count these bonds in the picture below, they are selected in red (the atom carbons are omitted, only the bonds are shown). This compound is generated by the plant to protect itself from the air oxidation. So it's a good antioxidant useful for us too, protecting our cells against the action of free radicals (potent oxidants), which are one of the main responsibles of cardiovascular diseases, cancer and aging.


(See the continuation in Part 2 below)
(See the continuation in Part 2 below)

Spinachs, parsley and plants in general are green because they contain chlorophyll, a pigment which enables the plant to carry on photosynthesis, transforming solar energy and carbon dioxide into chemical energy in the form of carbohydrates and oxygen. This is a process essential for life.

As you can see in the pic below, the structure of chlorophyll is very complicated, so let's simpy say that it contains a big ring with a magnesium atom in the center. Curiously, the structure of hemoglobine (the carrier of oxygen in our blood) is pretty similar to chlorophyll, though it has an atom of iron instead of magnesium in its center.

The chlorophyll masks the other colours in vegetables and as its amount decreases the rest of colours become evident. This explains for example why tomatoes are initially green and then become red when they ripen.



This is an example of how Chemistry is everywhere, sometimes more evident, and sometimes much less :-).
Spinachs, parsley and plants in general are green because they contain chlorophyll, a pigment which enables the plant to carry on photosynthesis, transforming solar energy and carbon dioxide into chemical energy in the form of carbohydrates and oxygen. This is a process essential for life.
As you can see in the pic below, the structure of chlorophyll is very complicated, so let's simpy say that it contains a big ring with a magnesium atom in the center. Curiously, the structure of hemoglobine (the carrier of oxygen in our blood) is pretty similar to chlorophyll, though it has an atom of iron instead of magnesium in its center.

The chlorophyll masks the other colours in vegetables and as its amount decreases the rest of colours become evident. This explains for example why tomatoes are initially green and then become red when they ripen.

This is an example of how Chemistry is everywhere, sometimes more evident, and sometimes much less :-).
As you can see in the pic below, the structure of chlorophyll is very complicated, so let's simpy say that it contains a big ring with a magnesium atom in the center. Curiously, the structure of hemoglobine (the carrier of oxygen in our blood) is pretty similar to chlorophyll, though it has an atom of iron instead of magnesium in its center.
The chlorophyll masks the other colours in vegetables and as its amount decreases the rest of colours become evident. This explains for example why tomatoes are initially green and then become red when they ripen.


This is an example of how Chemistry is everywhere, sometimes more evident, and sometimes much less :-).
The chlorophyll masks the other colours in vegetables and as its amount decreases the rest of colours become evident. This explains for example why tomatoes are initially green and then become red when they ripen.


This is an example of how Chemistry is everywhere, sometimes more evident, and sometimes much less :-).

This is an example of how Chemistry is everywhere, sometimes more evident, and sometimes much less :-).
This is an example of how Chemistry is everywhere, sometimes more evident, and sometimes much less :-).
How soap cleans?

There are substances which can be dissolved in water (salt for example), and others that can't (for example oil). Water and oil don't mix together, so if we try to clean an oily stain from a cloth or from the skin, water is not enough. We need soap.
Vegetables and colours - Part 1 White light from the sun contains all the wavelengths, but when it impacts on an object some of its wavelenghts are absorbed and some reflected. An object is coloured because of the light that it reflects. For example red objects reflect 'red' light, which is light with a long wavelength. Many vegetables and fruits are strongly coloured because they contain an especial kind of chemical compounds namedcarotenoids. These compounds have an area called choromophore, which absorbs and gives off particular wavelengths of light, generating the colour that we then perceive.

Vegetables and color - Part 2 
The pigment present in carrots is the betacarotene, with 9 linear conjugated double bonds, less than in lycopene so they are no red but orange (smaller wavelength than red, check it in the spectrum picture). This compound is also a potent antioxidant and besides it's transformed in our body into vitamin A, very important for the maintenance of healthy skin, good vision and a robust inmune system.
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