My Science School

Bicarbonate of iron interacts with the carbon dioxide and water forming sparingly soluble ferric hydroxide (brown). These sparingly soluble salts form the layer or ‘scales’ seen in utensils and boilers.

In filters, there is no boiling, still similar chemical changes take place, though to a much less extent, when the remnants of water dry up. Chlorides and sulphates do not undergo these chemical changes, but form residues due to evaporation of the water.

The usual way to avoid this trouble is by using de-mineralized water, that is, ordinary water filtered through permutit (sodium aluminum silicate), manganese salts (to remove iron) and modern ion-exchange resins. The last one frees water from all mineral salts.

All these filters naturally get clogged when in continuous use but can be regenerated in most cases by simple chemical treatment.

Normally, oxygen is carried to different parts of the body from the lungs by the blood using hemoglobin -the iron-containing, oxygen-carrying molecule of the red blood cells.

Hemoglobin is made up of a globular protein and four heme groups. The iron (in ferrous state) present in these heme complexes can bond to either an oxygen molecule or a water molecule or exchange them one for the other without much difficulty. It is because of this ability to exchange them, hemoglobin is able to pick up oxygen from the lungs, carry it to the body cells and bring back water in return.

The body cells ‘respire’ oxygen with the help of Myoglobin (hemoglobin like proteins present in the cells) and cytochrome (which function as electron carrier). One form of this cytochrome and hemoglobin are responsible for the sudden death due to cyanide poisoning.

When potassium cyanide is consumed, it splits into a potassium ion and a cyanide ion. The cyanide ion has a strong affinity to the ferrous ion than what oxygen has. As a result it occupies the site meant for oxygen in the hemoglobin. This process is irreversible and so it prevents transfer of oxygen.

Also, one form of cytochrome, designated as cytochrome-a, also binds with the cyanide ion and stabilizes the iron to such an extent that it does not take part in the electron transfer to the cell. This prevents oxygen in take by the cell. The symptoms of cyanide poisoning are giddiness, headache and bluish tinge of the skin. All these are indicators of lack of oxygen supply to various parts of the body. If not treated immediately, unconsciousness and death will follow.

Inhalation of amyl nitrate or injection of sodium nitrite to oxidize some of the hemoglobin to methymoglobin provides relief. Methymoglobin binds to cyanide ion more tightly than hemoglobin or cytochrome-a and helps in the removal of cyanide from the system. Carbon monoxide (CO) also has a similar effect when inhaled. It forms a stable compound called carboxy hemoglobin and deprives it of its oxygen carrying capacity. 

 Glucose exists in the crystalline form. When dissolved in water, the crystal structure is broken. To break the bonds in the crystal energy is required. This is obtained from the water itself and so its temperature is reduced. Chemists call this an endothermic process. But considering a similar reaction, the dissolution of salt (sodium chloride) in water.

Though this is also an endothermic process the heat transfer involved is very less. (Moreover there are other interactions of the sodium and chloride ions with water, which are exothermic in nature).

Strong exothermic effects are observed in certain cases where the substances interact strongly with water molecules. For example, dissolution of washing soda (sodium carbonate) or sodium hydroxide. 

Fire involves a chemical reaction between fuel and atmospheric oxygen.  Once initiated it is self-sustaining, generates high temperatures and release a combination of heat, light, noxious gases and particulate matter.

The visible flame is the region in which this chemical process occurs and so flame is essentially a gas phase phenomenon. For flaming combustion to occur, solid and liquid fuels must be converted into gaseous form.

 For liquid fuels this is achieved by evaporative boiling. For solid fuels, the solid is chemically decomposed through the process of paralysis to generate volatile gases.

A flame is a region containing very hot atoms. At high enough temperatures all atoms will emit energy in the form of light as their electrons, which have been prompted to higher energy levels by absorbing heat energy, fall to lower energy states. Because this light is emitted in discrete quanta according to the relationship E= hf (where E=energy, h=Planck’s constant and f= frequency), flame colour is related to the magnitude of the energy quantum which is transformed to light.

This can most easily be seen with a Bunsen burner. A Bunsen burner that has a choked air supply burns cool, the light emissions from carbon atoms are relatively low in energy and appear more red or orange.

However, when the Bunsen is allowed air so that combustion is complete, the flame is hotter and the light emitted is of a higher energy and frequency and appears blue.

The luminescence of a flame is only of the story. The structure of the flame region is important to understand too. The flame area in a normal combustion environment, such as an open-air bonfire, is structured by convention currents which form as hotter, lighter air rises and allows cooler fresh air to replace it.

It is this channeling effect and movement of air that shapes the dancing flames. It is interesting that in space, in zero gravity, the hotter and cooler air cannot move by convection, so flames take on weird shapes and may be stifled by their own combustion products. 

Fingerprint formation is like the growth of capillaries and blood vessels in angiogenesis. The pattern is not strictly determined by the genetic code but by small variables in growth factor concentrations and hormones within the tissue. There are so many variables during fingerprint formation that it would be impossible for two to be alike. However it is not totally random, perhaps having more in common with a chaotic system than a random system.

It is believed that the development of a unique fingerprint ultimately results from a combination of gene-environment interactions. One of the environmental factors is the so-called intrauterine forces such as the flow of amniotic fluid around the fetus. Because identical twins are situated in different parts of the womb during development (although they are not static), each fetus encounters slightly different intrauterine forces from their sibling, and so a unique fingerprint is born.

            Your genes specify only your biochemistry and through it, your general body plan. The pattern of your fingerprints forms rather in the way that wrinkles form over cooling custard. At most you may predict, say, the fineness of the wrinkles and their general pattern. Fingerprints are just one example. Many of your features could mark you out from any clone. Your genome only controls gross characteristics such as the rates at which the skin and its underlying attachments develop and grow. Even if there is no way for genes to specify everything exactly, there is no way the genome could carry enough information for the details. If our genomes had to specify everything, we would not be here. But, while the consequences of imperfect specification are usually trivial, they may have more serious effects. A minor distortion of a blood vessel could give poor blood flow or an aneurysm, and the branching and interconnection of brain cells affect mental aptitudes. That is why, though bright parents tend to have bright children, dimmer ones may have a child genius and vice versa.

 Cobra venom consists of 10 different enzymes, several different types of neurotoxins, cardio-toxins, cytotoxins, dendrotoxins and fasciculins (for example, lysocephalins, lysolecithins which are phospholipids). Snakes of the elapidae family (for example cobras, kraits and mambas) have venoms that kill primarily through neuro-muscular paralysis. It contains 60-75 amino acids and target nicotinic cholinoceptors in the muscle cell membranes which are sensitive to a chemical transmitter, acetylcholine. (Acetylcholine is released from nerve endings in response to an electrical impulse in the nerves.) The amino acids in snake’s venom block the junction between the nerves and the muscle. Scorpion’s venom consists of an arsenal of toxic compounds which contain 37 amino acids called charybdotoxin.

            When a scorpion stings these acids incapacitate the nerve cells causing severe pain, by rigidly binding with sulphur bonds unlike the snake’s toxin which binds by a ligand series. Moreover snake’s venom is digestible, but scorpion’s venom is not          

            Plants can prevent pollution of environment in many ways. However, the answer is restricted to prevention of air pollution by trees.

            The major components of atmosphere are nitrogen (78.08 per cent) and oxygen (20.95 per cent) (major) with minor components are argon and carbon dioxide (0.0314 per cent) and many trace elements such as neon, helium, nitrous oxide, methane, carbon monoxide, sulphur dioxide, ozone, ammonia and aerosols (colloidal sized particles) are also present.

            The ratio of these components is changing very fast due to increased human activities like fossil fuel burning, afforestation and changes in land use. They result in the liberation of tones of carbon dioxide, carbon monoxide, methane and aerosols into the atmosphere. The server human interference over the last century is said to have strained the buffering capability of nature.

            Trees help reduce the pollution in more than one way. First, they act as sink for carbon dioxide. Through photosynthesis they synthesize carbohydrates using carbon dioxide, water and sunlight. This way thousands of tonnes of carbon dioxide are trapped by the trees. By the same process, trees release oxygen, which is needed by other living organisms. They also help in cooling of the atmosphere by transpiration, a process in which water is given up by plants as vapour. I addition, aerosols and dust particles (components of atmosphere pollution) settle on the dense foliage of trees. Thus trees, especially the tall ones with dense foliage around houses and industrial establishments, reduce aerosol and dust pollution by acting as barriers or curtains.

            High temperatures above 92 degrees have been implicated in the increase f bitterness in fruits, although there is no evidence to support this. Conversely more bitter cucumbers are seen growing during the cooler growing season.

  Most of the mushrooms have a cap called pileus and a stem called stipe. The cap on its underside consists of gills which bear the spora producing structures. Important to the identification of a species are the properties of cap, the shape and colour of the gills, the way in which they are joined to the stem, presence or absence of sheath, scales and annulus ring etc. The most poisonous mushrooms are species of Amanita which come under the family Amanitaceae and the most delicious edible mushrooms are species of Agaricus (Button mushroom) which come under the family Agaricaceae. In general the fruit bodies of Amanita species can be distinguished from the Agaricus species by the following characters.

In Amanita species the pileus on its upper surface bears the scales and the stipe bears at its base a sheath called Volva. These scales and sheaths are absent in the fruit bodies of Agaricus species.

Volvariella (Paddy straw mushroom) is also having Volva at the base of the stipe as in Amanita. But it is an edible mushroom and also commonly cultivated. The Oyster mushroom namely Pleurotus is another edible one. This can be identified by its stem at the side of the cap and gills on the under surface of the cap. Boletus (Penny bun mushroom) and Lactarius (milk cap) are also edible members which grow in wild condition but not cultivable. Among these Boletus can be identified by its dense layer of tubes instead of gills on the underside of the cap.

The familiarity in distinguishing the poisonous and nonpoisonous mushrooms is needed only when we collect the wild fungi from the field for our diet table. But this problem will not arise in the case of edible fungi which are cultivated for this purpose.

 Left alone for two hours, the drink would slowly lose the gas and go flat. Sodium chloride particles seem to provide an especially good surface for gas to collect on, form bubbles and quickly rise to the surface and escape.

Naturally occurring water contains quite a few substances dissolved in it. For example, it contains gases such as oxygen and carbon dioxide, sulphates and carbonates of calcium and magnesium, and other elements such as iron depending the nature of the soil. These constitutes impart not only taste but also hardness to the water. Due to boiling, the dissolved gases are released and hardness is removed. Insoluble carbonates and hydroxides are formed which get deposited on the surfaces and the bottom of the vessel as scales. Their separation from water deprives it of its taste.

            Cold water extinguishes fire faster. It’s easy availability, non-toxicity, high specific heat, low    boiling point, high latent heat of evaporation, high volume expansion, water to steam, makes it suitable for fire extinguishing.

        In case hot water is used, the heat absorbed from the source (fire), by a definite quantity, to reach its boiling point will be far lesser vis-a-vis the same quantity of cold water. However, the other parameters will remain the same. Colder the water, faster would be the extinction of the fire.

 Coloured bands on soap bubbles and oil layers are caused by interference of light waves with themselves. Sunlight is a composite of seven colours (violet, indigo, blue, green, yellow, orange and red, in that order) each of which lies in a specific wavelength range. For example, violet light has a wavelength of 380 nanometers (one nanometer is a billionth of a metre) and red, above 600 nm.

Artificial diamonds have the same structure, density and hardness as natural diamonds, but are very small. They are also opaque to x-rays. Hence they are used mostly for making hard-edged cutting tools and dies and for cutting and polishing natural diamonds, and not for making ornaments.

The moulds in the shape of cubes are made by mixing cement with equal proportions of three grades of sand – coarse, medium and fine. This is cast in cubes of side about 7.07 cm so that a surface area of 50 square centimeters is obtained. Cubes cast thus are removed after 24 hours and cured in water for 28 days. Then they are subject to compression tests.

 The maximum stress in Newton/square mm which they can withstand is measured and given as their compressive strength.

If this lies between 33 and 43 N/square mm, it is termed as 33 grade cement. Similarly, if it lies between 43 and 53 N/square mm, it is 43 grade cement and if it is more than 53 N/square mm, it is 53 grade cement.  To avoid any discrepancies, always only batches of three cubes are subject to compression tests and their average is taken. Generally 53 grade cement is used for making high strength concretes.