Concept of pH in Chemistry

Although the pH of a lake or polluted stream is seldom reported in the media, the people who are monitoring the health of the lake water record it daily religiously. But pH is quite an important physical property of water. pH of a stream gives an indication about the salts and other soluble matter present in the water. These soluble salts affect the organisms living in the water. Also changing pH in a stream can be an indicator of increasing pollution or some other environmental factor.

As we know life on our planet is based on the water. Water is a unique solvent as it dissolves a number of chemicals in it. Water molecule is a simple one with H2O as its formula indicating 2 hydrogen atoms joined to 1 oxygen atom. It V shaped geometry imparts it high polarity with which it is able to break down many salt molecules into individual ions called cations and anions. As such water is slightly ionized into equivalent amounts of hydrogen and hydroxyl ions. The value is 10-07 equivalents, a very very tiny value indeed. But this small value is enough to do all the chemistry. When chemicals dissolve in it, the values of hydrogen and hydroxyl ions become unequal. Particularly when any compound containing hydrogen ions is added to water, hydrogen ions become predominant and solution is said to become acidic and such chemicals are called acids. Examples of acids are hydrochloric acid, nitric acid, citric acid and sulphuric acid. On the other hand, when any chemical which have hydroxyl ions is added to water, hydroxyl ions predominate and water becomes basic and such chemicals are called bases.  Examples of bases are sodium hydroxide, washing soda and potassium hydroxide.

pH is a measure of how acidic/basic water is. It is defined as the minus logarithm of hydrogen ions concentration. Since -log[10-07] is 7, the pH of pure water is 7. The range goes from 0-14. Any solution having pH value less than 7 is acidic and above 7 is basic in nature.

The pH of any natural water determines availability of nutrients like phosphorus, nitrogen, and carbon for aquatic life. Many nutrients like phosphorous are very sensitive to pH since it exists in different forms at different pH values. Only a particualr form is assimilated by the organism.

Similarly, pH determines the solubility of heavy metals which are generally toxic in nature. Heavy metals are generally more soluble at lower pH and hence lower pH gives a warning about the possibility of these heavier and poisonous metals.

pH of Battery acid is 1, vinegar is about 3, milk slightly above 6, baking soda between 8 and 9 & ammonia solution about 12.Diagram of pH. pH 1=battery acid, 2=lemon juice, 3-vinegar, 6.5=milk, 8.5=baking soda, sea water, 10.5=Milk of Magnesia, 12=ammonia, 13=lye. ph 3 to 4=Adult fish die. ph 4-5=Fish reproductionaffected. pH 5-6.5=Normal range for precipitat on. pH 6-8=Normal range of stream pH. pH 1-5=Acid rain.

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View from Window

The view from from window of my room at 4 O’clock in the Evening:
It is 4 O’clock in the evening. The sunshine is becoming pale at the approach of the evening. The mornings, evenings and nights are becoming cooler. Sky is still clear. Sitting in the same room of my home on the third floor, I am looking at the scene out side from the window.
The outline of trees looks like the drawing of a child making lines with a pencil which are not straight but serrated. The shadows and lights are playing exclusive games in the branches which are swaying due to strong breeze. When one is there other is gone and vice versa. There is a meadow below and cows and buffaloes are grazing lazily. As they graze, cranes accompany them to catch the insects which are scurried due to the grazing animals. Many of them can be seen perching over the tops of animals.
The shadows of the rows of trees are beginning to lengthen and crawling over over the fields and are moving towards my room. Some boys are trying to catch fish from a pond near the edge of tree rows. The pond is irregular in shape and its still water looks shines due to sunlight falling on it. From above it looks like a shard of glass, very longish and narrow. White cranes and black egrets are plunging into the water occasionally and rest of the time sit on the nearby bushes.
Airplanes keep on coming at very low height as they are descending preparing for landing at Chandigarh airport which is very near. Sometimes very huge cargo plane is seen passing very near our buildings with deafening noise.

Evening

Sitting in the room of my home which has large glass panels opening in West direction, I am looking at the Sun going down leaving behind a copper colored hue in the West. The sky is smeared with mild clouds of different transparencies. There are thick columns of of poplar trees which are now loosing their individuality and taking on dark shroud. There are kites flying and sometimes swooping down on their prey. Snow white cranes are leaving the grazing grass grounds and flying towards their homes. Even as I am typing these words the whole scene is becoming ambiguous and soon darkness will swallow the day.

Animals cannot digest Cellulose

Most plants synthesize cellulose which they use to give strength to their bodies and make them withstand the vagaries of storms. It gives the shape to the trees and branches then expand the tree. Cellulose becomes the wood when trees become mature. Furniture is made of this material. It is obvious that cellulose is insoluble in water otherwise no one will use it in construction and furniture.

Cellulose and starch and other carbohydrates consist of glucose molecules which are arranged in chains of different styles. In starch, two chains are intertwined. These chains get separated on boiling the starch in water. This caused the chains to disperse in the water increasing its viscosity. Such starch is called pre-gelatinized starch.

On the other hand, cellulose structure is such that chains are not dispersed and wood remains unaffected in water. Glucose is the basic unit of sugar which is used by animals like humans for obtaining energy to keep the body running.

How do then we assimilate higher sugars like starch. They have to broken down to glucose units. The enzymes found in humans and other animals allow them to digest and metabolize many, but not all, biomolecules. Cellulose is one example of a molecule that defies digestion in many animals.

But the slight difference in the way the glucose molecules are hooked together in starch compared with how they are hooked together in cellulose makes a big difference in their digestibility.

Humans and many other higher animals have the enzyme required to break the bonds in starch, releasing glucose. The particular enzyme is called alpha-amylase.But because the shape of the linkage is different in cellulose, the same enzyme will not work. In fact, where cellulose is concerned, humans do not have an enzyme that will work.

As it turns out, most humans eat a fair amount of cellulose in the form of fruits and vegetables. Although we cannot digest it, the cellulose serves as roughage or fiber that gives food bulk and keeps it moving through the digestive system. In the end, all of the undigested material ends up being eliminated as feces.

Maybe you are wondering how animals such as cattle, sheep, deer, and goats thrive on a diet of grass or other cellulose-rich food. Can they digest cellulose when humans cannot? The answer is no. None of these animals have the enzymes required to digest cellulose. Instead they rely on colonies of microorganisms living in their digestive systems.

These simple microorganisms have the correct enzymes to digest the cellulose and to reassemble the products into starches and proteins. From these products, grazing animals acquire their nutrients. The special relationship between these animals and their resident microbes is called symbiosis—two organisms living with each other to the benefit of both.

Darkness

Darkness I said. But you may say light only acquires meaning thanks to darkness. Contrary to my expectations, it has turned out to be the opposite. The things which shone from afar turned out to be dark. Darkness was hidden behind the light, lies sugar coated with sweet talk were forced down my gullet.From the great distance, things looked prettier like they say that grass looks greener on the other side of the fence. I don’t blame the ones who gave me wrong impressions. what was the need to do that? Guided by this wrong impression, I came.

From the time of setting my first foot in this place, reality began to unfold. Coverings began to lift and fade away to reveal the dark truths. For some time I thought that it may be my false doubts but as the time went by, everything begun to become clear like water in a pool which became turbid after a stone was thrown begins to again become clearer. I have been shown the flip side, or the underbelly of everything. My hopes soured. I became even more distanced sitting nearer. When I was physically miles away, I was more closer than when I am closer physically I am miles away mentally.

Observing the Nature

How often do we leisurely watch the nature around us? General answer will be not often. Do we sit out in the evening and watch the sun going down, its glow becoming golden, and shadows lengthening and blinking through the chinks in the trees? Do we watch the groups of birds flying towards their homes after spending their day in a far off place where the food is available to forage? Why, in the first place, they don’t make their resting places near the food. May be the supply is not available at one place throughout the year and their resting places are at optimum distance from the foraging places. Why do they always fly in the groups? Is not their pressure or competition for food? Is the father of Evolution theory listening?

After reeling under the sweltering heat for many days, if there is rain, it is like a fresh breath of life. The parched land is drenched with water pushing out the air filled with earth’s aromas into the atmosphere and filling our nostrils with ecstasy. The accompanying wind rushes into the branches which sway from side to side at the top such as in the mighty silver oak trees. One wonders how the topmost leaves are receiving their requirement of water and nutrients. In optimistic hope of supply from the soil, additionally they must be conserving the water by reducing their stomata counts, As they are in the top, they have the benefit of plenty of sunlight. I also wonder if the leaves at the top are in any sort of communication with those at the lower branches.

Rain patters on the tins of roofs. Water begins to flow over the soil surface seeking places which are at lower level to become pooled there. The dust on the leaves which was choking the plants breath is washed up and translucency returns. Sometimes after the rain, sun comes out and everything shines resplendently. The weather becomes bearable.

Color Changes in Chameleons

We have been told that chameleons change their color to conceal themselves by blending in with their surroundings. In fact, a person who is changeable or inconstant in behavior is called chameleon. It has been proved that the facts are something else. And it is a myth. .  Most of the reason chameleons change colour is as a signal, a visual signal of mood and aggression, territory and mating behaviour.

The chameleons are master molecular scientists. Their skin has transparent layers in which different color compounds are tucked away. These specialized cells store the different color compounds and these cells are called chromatophores. They contain various pigments.  These are xanthophores, containing particular specialised pigments that have a yellow colour.  Beneath that are pigment cells which are called erythrophores which have a red colour in them.  Beneath that, another layer of cells called iridiphores have a blue coloured pigment called guanine, which is actually also used in making DNA.  And underneath that is another layer of cells called melanophores which have a brown pigment – melanin – in them.

As such these pigments are confined to sacs. Depending on the signals from the brain, pigments are leaked and depending on the amounts released, mixed colors are formed. This is like artist mixing the different amounts of colors in the color palette. So if you mix red and yellow, you get orange for example, and this is how chameleons do this.  They mix different contributions of these chromatophores.

So a calm chameleon is a pale greeny colour.  When it gets angry, it might go bright yellow, and when it wants to mate, it basically turns on every possible colour it can which shows that it’s in the mood.  This is not unique to chameleons.  Other animals also have these chromatophores. Cuttlefish are another very elegant example of how this works.  So it’s not so much to do with camouflage.  It’s more to do with communication.

Fascination to Coloring their World

“Thou shalt make the tabernacle with ten curtains of twisted linen, and blue and purple and scarlet…(Exodus 26:1)”
These lines from Holy book “Bible” show the human desire for colors. It has been always been fascinated with color. The competitors of our forefather “homo sapiens”, prepared their dead for burial by coating their bodies with red ochre, which is actually Ferric oxide. After them, Cro-Magnon made cave paintings using for colors yellow and red iron oxides, black manganese dioxide and white clays. These are natural material available as rocks and salts for tens of thousands of years. This continued until the invention of weaving and clothes.

Pigments had been made by combining colored minerals with a vehicle, such as oil or mud, that would adhere to a surface. When the paste-like pigments were applied to fabric, the cloth became stiff, and the coloring material soon washed or fell out. Pigments wouldn’t
work—cloth could only be colored by dyes, organic molecules that bond directly to the textile. So colors which adhered to cloth and became insoluble afterwards. And also they should be soluble in the water. This was usually achieved by adding chemical compounds like alum which contain metallic ions which act as binder for cloth and dye.