Category Chemistry

What is smoke?

          Whenever wood, coal or some other substance burns, smoke comes out. Smoke is produced due to the incomplete combustion of fuels. If complete combustion of fuels takes place, no smoke will be produced. In fact smoke is a colloid of solid particles in a gaseous form.

          Most of the fuels contain carbon, hydrogen, oxygen, nitrogen and small quantities of sulphur. When any fuel burns, we get carbon dioxide, water vapour, nitrogen and traces of sulphur dioxide. For the complete combustion of fuels a large quantity of oxygen is required because burning is a process of oxidation. Due to the lack of oxygen, fuels do not burn completely. As a result of this smoke is produced. Smoke mainly consists of carbon dioxide, water vapour and carbon particles. When the number of carbon particles present in the smoke is large, it appears gray or dark. These very carbon particles get deposited on the walls of the chimneys. This deposit is called soot.

          Smoke is the biggest pollutant of air and is very harmful from the health point of view. Today it has become a major problem in the cities. If it does not get scattered by wind, the atmosphere of the cities becomes highly foggy. Smoke is particularly harmful for the heart and lungs and is the cause of many diseases. It is also harmful to the eyes.

          However, in certain respects, smoke is useful also. It is used to protect the orchards from cold. In wars, smoke helps in camouflaging. It is also helpful in rain formation by enabling the water vapour to condense on its particles. 

How are icebergs formed?

          In the Southern Hemisphere, the Antarctic ice sheet overflows its land support to form shelves of ice on the sea; huge pieces, as much as 200 km. across, break off to form icebergs. In Northern Hemisphere icebergs are generally not over 150 metres across. However most icebergs are from some 20 glaciers on the west coast of Greenland. When glaciers, drifting from mountains and valleys, reach the sea, they got broken into big pieces by sea waves and tides. These big pieces of ice are called icebergs. However there are some glaciers which do not break even after floating for long distances in the sea and appear like mountains of ice.

          The sizes of the different icebergs vary. The smallest iceberg measures 5 to 6 metres in length and breadth but the bigger ones might be hundreds of metres long. Some icebergs with lengths and breadths of half a kilometre have been seen floating in the oceans. They float in sea water because ice is lighter than water. Their one-tenth part remains above water and the remaining under water. For example, if a 50 metre high iceberg is seen above water, then 450 metres of it will be under water. These icebergs contain huge quantities of snow. Some of them may contain 200,000,000 tons of ice. As an iceberg floats, some of the ice melts and pieces break off. Eventually, it completely disappears.

          Because of their huge weight and volume, the icebergs do not move in the sea on their own. They are pushed ahead by the sea waves. They are very dangerous for ships. A collision with them can cause a ship wreck. Though they can be detected with the help of modern instruments, yet mishaps do take place occasionally. On 14th April 1912, a ship named Titanic was broken to pieces when it collided with an iceberg. This ship was sailing to New York; 1513 passengers, who were aboard this ship lost their lives.

          A similar accident took place on January 30, 1959 when the ship Hans Hedtoft collided with an iceberg in southern Greenland and was wrecked. Now the United States and other countries have formed an International Ice Patrol. The patrol uses ships, planes and radars to locate icebergs.

 

Why do we perspire?

          Our body is like a furnace. The food we eat acts like fuel inside the body. It produces heat energy by the process of oxidation. Through this process about 2500 calories of heat is produced every day which can boil 25 kgs of water at 0°C. But what happens to this heat in the body?

          In our body certain metabolic activities are constantly taking place which do not normally allow the temperature to go beyond 98.4° F. Perspiration is one of the means through which the body furnace keeps its temperature normal. In fact, the body temperature is controlled by the ‘temperature centre’ located in the brain. This centre has three parts: control centre, heating centre and cooling centre.

          If the temperature of the blood falls below the normal due to some reason, the heating centre starts operating immediately. At the same time some special glands produce certain combustible chemicals which are used by our muscles and liver to raise the internal temperature of the body to the normal degree.

          On the other hand if the body temperature rises for some reasons the cooling centre goes to work. The process of oxidation slows down. Sweat glands start excreting sweat. Water, urea and some salts come out with the sweat. The sweat glands work fast only when the internal temperature of the body goes up. Sweat evaporates with the help of the body heat and this produces a cooling effect in the body. This process is similar to that of cooling of water in a pitcher during summer. Evaporation always causes cooling. Sweat, therefore, is a very effective process of controlling the body temperature. It also cleanses the internal parts. Many substances, harmful to the body, are excreted out through the millions of pores of the skin in the form of sweat. When the humidity is high, sweating causes uneasiness because the rate of evaporation under humid conditions decreases.

How is soil formed?

          Soil is the upper most surface layer of the earth in which plants grow and on which directly or indirectly, all life depends. It is composed of rocks, minerals, organic matter, water and air. It did not take one or two days for the soil to form but millions of years. Do you know how soil is formed?

          Millions of years ago, soil existed in the form of rocks. Since then weather and other natural forces like wind, rain, snow, water, heat etc. had been interacting with the rocks to break them into smaller fragments. These forces further converted the rock-pieces into sand. Bacteria, carbonic acid and other micro-organisms converted this sand into soil. In course of time bacteria converted the bodies of dead plants and animals also into soil.

          Soil is classified according to its colour, texture, chemical properties and climate. Colours of soil range from yellow and red to black. Soils are also categorized as acidic, alkaline and neutral. Extremely acidic or alkaline soil does not support plants. 

          There are three main types of soil a) Pedalfers – associated with temperature, humid climate, contain iron and aluminium salts, b) pedocalo – associated with low rainfall regions, contain soluable substances such as calcium carbonate and other salts and c) Laterites – tropical red or yellow soils heavily leached and rich in iron and aluminium. Based upon soil classifications, modern farming and plantation are made to yield maximum returns.

          An organic matter called humus is constantly being added to the parent soil. Humus makes the soil more fertile.

          Deep, well developed soil is divided into four layers called horizons. The top layer, where most plants grow, is called the A-horizon or top soil. This layer is rich in organic material and contains some minerals. The next is called B-horizon or sub soil. It is rich in minerals, especially in clay, but with little or no organic matter. Farmers often mix the A-and B-horizons by ploughing. The third is called C-horizon and it is a layer of weathered and shattered rocks. It is called the fragmented rock. It is quite similar to parent soil. The last layer is D-horizon or bed rocks. 

What are pain relievers?

          A pain reliever is a drug that reduces pain without causing unconsciousness or complete loss of feeling. In medical terminology, they are called analgesics. There are two main types of analgesics: The peripherally-acting analgesics or non-narcotic pain-relievers and the centrally acting analgesics or narcotic pain-relievers.

          The first type acts on any pain associated with muscles or bones or their related structures. Hence these are called peripherally-acting analgesics or ‘mild analgesics’. The most common of these is aspirin. Its active constituent is acetylsalicylic acid. It was first synthesized in 1899, and produced in huge commercial quantities ever since. Other analgesics of this group include analgin and paracetamol. These are used to relieve headaches, rheumatism and other body pains.

          The second groups of pain killers, the centrally-acting analgesics are very potent drugs and include substances derived from opium, an extract of the poppy plant. Two such analgesics are morphine and heroin. In the brain they depress the activity of the cortex, and thalamus which is the part that receives messages from the body’s pain receptors. They are very effective and act instantly when injected into a muscle or vein. They are only used by physicians for relieving intense pain of those suffering from cancer, heart attack or severe injuries involving broken bones or wounds. Some common drugs of this group are Codeine, Pentazocine and Ethoheptazine.

          Both types of analgesics have a number of side effects. For example, aspirin can irritate the stomach, cause indigestion or in serious cases it may even lead to an ulcer. If used indiscriminately, it may cause anaemia.

          Morphine drugs can cause nausea and vomiting, but this side-effect can be blocked by giving the drug Cyclizine along with it. Morphine and its allied drugs can cause addiction when used over a prolonged period.

          Some other analgesics such as antipyretics are used to bring down fever. In severe cases or while carrying out a surgical operation, doctors apply many anaesthetic drugs to deaden pain.

          These drugs are available under different brand names. Aspirin is available in the brand name of Disprin, Mejoral etc.; paracetamol is available in the name of Calpol, Crocin etc. Novalgin is an analgin whereas Fortwin is a brand of Pentazocine. It is always advisable to check the constituents before buying these drugs. 

How can we test the purity of milk?

             The instrument used to assess the purity of milk is called a ‘lactometer’. It is a cylindrical vessel made by blowing a glass tube. One end of the glass tube is blown in the form of a bulb and filled with mercury. The other end is blown in the form of a thin tube and sealed. For calibration it is dipped in pure milk. The point up to which it sinks in the pure milk is marked ‘M’. After that it is put in water and is marked ‘W’ at the point up to which it sinks in water. It sinks less in milk than in water because milk is denser than water. The portion between ‘M’ and ‘W’ is divided into three parts and marked as 3, 2 and 1 to indicate the level of purity.

              Whenever we want to test the purity of milk, the instrument is put in milk. If it sinks up to the mark ‘M’, the milk is pure. If the milk is not pure, but mixed with water, it would sink to a mark higher than ‘M’. When the instrument stands at the mark 3, the milk is 75% pure. At the mark 2, the purity is only 50%. Mark 1 indicates a purity of 25%.

            Even though lactometer is commonly used to measure the purity of milk, yet, it is not a very reliable instrument. It has been observed that in the case of skimmed milk (denser than pure milk) that the lactometer fails to give the correct assessment of the purity, if the density of the skimmed milk is made equal to that of the pure milk by adding water in an appropriate proportion.