In Search of Chemist’s pure water

Chemist’s pure water which is formulated as H2O exists only in the theory. In the laboratory too, it has to be prepared from the water from the tap. The reason isits high polarity and very dielectric constant which makes it is a potent solvent. It can dissolve ionic inorganic salts, polar organic compounds, acidic, basic and polar gases. It also carries suspended matter like clay particles which are in the form of colloids. Some of these are loosely suspended and separate out with time by sedimentation and other are stable and has to be destabilized by using defloucculants to settle them out. For example, the river water continuously interacts with the rocks and soil during its flow and leaches many inorganic salts of alkali metals, alkaline earth metals in appreciable amounts and many other metal ions in trace amounts. It can absorb the lower molecular weight organic acids like formic acid and acetic acids. Gases are trapped in two ways by water. First category are gases which are acidic like carbondioxide and oxides of nitrogen, sulphur dioxide etc reacts with water and render it acidic and basic like ammonia react with it to form basic solutions. Another way by which water traps the molecules of non polar gases like oxygen, methane etc is that there are cavities in the grid of water molecules where these gases are trapped through weak Van der Wall forces.

Not only that, when water freezes, in the lattice it creates, gaseous hydrocarbons are trapped if certain conditions like availability of these gases at the time of freezing, pressure, temperature. If the conditions fall into the favorable envelope, gases are trapped. These are called gas hydrates. In fact, it has been estimated that vast amounts of methane is trapped world over in this form. Technology is being developed to tap the resource in a safe, environmental friendly and economically feasible way.

Chemist has to remove all these impurities to achieve a tentative pure water. The degree of purification depends upon the kind of experiment. For example, for the ion chromatography where presence of ions is determined at ppb or ppm level, the water used in this work has to be free from the ions under determination in a sample. This water is prepared with sophisticated water purifier called ultra purifier which removes suspended matter, kills bacteria and removes every ion present to negligible amounts. For ordinary work on a gross level determations, onetime distilled water will do the work.

This also does not last long as it is continuously absorb the gases from the environment if it is not sealed. If your laboratory is located near a highway with high volume of vehicles then due to the emission of the acidic nitrogen oxides, this water immediately turns acidic. Thus even during the conducting of experiment, special care using isolating techniques has to be taken if the correct results are to be achieved. In the analytical work, the procedures specially mention the freshly distilled water to be used.

So whenever we speak of water, it is not the pure H2O but a mixture of different salts and gases dissolved in the chemistry water. Some of these ions are required for human bodies but these should be within limits.

So the chemical composition of water is very important to know it’s potability for drinking purposes. Generally, in most of the cases treatments are necessary to make it fit for drinking.

Changes in Periodic Table of Chemicals….

We know that everything in the universe is made from the atoms. They are the basic building entities. Atoms are not solid entities but are made of dense nuclei surrounded by fuzzy cloud of electrons whizzing in the outer. Nucleus is made of protons and neutrons. Things don’t not end here. Nature is very complex. Even the atoms of same elements can have different number of neutrons making them have different weights. Such atoms are called isotopes. Atoms of same element or different elements can combine in umpteen ways resulting in diverse molecules and different substances from very simple molecules like water and methane to complex molecules containing thousands of atoms.
Many elements have more than one isotopes. One of these is the most abundant and is for all practical purposes considered as the representative. Other isotopes exist in very low abundance. All elements can be divided into different groups in which the chemical and physical properties vary in periodic manner.
Earlier, we remember the chemical composition of compounds was determined by chemical methods using classical techniques. From the elements proportions an empirical formula was derived. Methods gave numbers of constituent elements which have to be rounded off.this happened due to the inherent limitations of determinations. So generally the molecular weights were either whole numbers or at most rounded off to first decimal place.
Thanks to the extremely accurate measurements now available with advancement of science, we are measure the abundance of all isotopes very accurately. Ten elements namely hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine and thallium which have one or more isotopes have now been selected whose atomic weights shall be displayed in the periodic table as a range. For example, the atomic weight of boron (atomic number 5) is currently written as 10.811. On the new periodic table, it will be given as an interval—from 10.806 to 10.821. This might not seem like a big change—and it is very small—but such a change can be critical to calculations in scientific research and for industrial applications. Also, chemistry teachers and students will have to learn how to use the new weight intervals.
Since now we the abundance and atomic weights of each isotope very accurately, the range will fix the upper and lower limits. By comparing the atomic weight of a particular element in a sample and mapping it on the range interval we can know the source of sample.
For example, oxygen atoms in the water samples contain isotopes. During evaporation fractionation occurs. Water molecules with lighter oxygen atoms evaporate faster leaving behind the water with heavier isotopes.
Similarly, the atomic weight of carbon is smaller in performance-enhancing drugs than in natural testosterone meaning natural testosterone contains higher abundance if heavier carbon atoms. This difference can be used to test whether athletes used these drugs to improve their performance.
The new atomic weight measurements not only account for the presence of isotopes but also consider their relative concentrations in the universe. Carbon 12 makes up 98.89% of all carbon, while carbon 13 is 1.11%, and the natural abundance of carbon 14 is 0.0000000001%. So, the weight interval for carbon will lean more heavily toward carbon 12 and range from 12.0096 to 12.0116. This range will replace the average atomic weight for carbon listed in any chemistry textbook, which is 12.011.

Is there life on Mars? Again Microbes hold the key

Earliest life of single cell evolved into 3 branches having distinct traits. The branches further subdivide into more branches on the evolutionary tree of life called Phylogenetic tree of life. The first three branches are called Bacteria, archaea and Eucaryota.

450px-Phylogenetic_tree

As we can see in this tree, there is a member of archaea family with the name Methanogen. This microbe holds the answer for presence of vast quantities of methane which is trapped inside the ice cages called methane hydrates. These hydrates are found on Earth in the permafrost regions having very low temperatures or under the deep sea floor. Water molecules arrange themselves into octahedral cubes in which molecules of many compounds can fit into them. These are called clathrate compounds. These structures are very fragile and as soon as the overhead pressure is reduced or temperature increases, the structure crumbles and gas is released. So special technology is required to produce the methane from hydrates. In US, carbon dioxide was pumped into the hydrate layer. It substituted into the cages releasing the methane free. It served two important purposes. First the production of fuel gas methane and sequestration of unwanted carbon dioxide. These microbes use carbon dioxide and hydrogen to make their food and also generate methane and water. These microbes are very enterprising. They can use alternative sources of carbon like acetates which are the products formed by another kind of bacteria by breaking the macro-molecules present in the buried organic matter, for their food. One thing these tiny beings hate is oxygen. They work in anaerobic environments like deep buried locations.

Now this microbe is being held responsible for the methane gas found on Mars indicating that there is life on the planet. It means Mars is not a dead planet. Professor James Kasting said if there is anything alive on Mars at this time in its history, it would probably be some form of microbial life living deep beneath the planet’s surface. Perhaps the most likely form of microbial life is a type of bacteria known as methanogenic bacteria, or methanogens for short. The CO2 needed by the methanogens could presumably come from the atmosphere. The H2 could come from chemical reactions between water and certain types of rocks, specifically magnesium- and iron-rich basalts. Such rocks are found on certain parts of the seafloor today on Earth. When they react with water, they form minerals called serpentine minerals. In the process, hydrogen is produced. The reaction that produces methane is thermodynamically favorable, so Methanogens could use the energy released by this reaction to drive their metabolism. Microbes can make many reactions happen at much lower temperature by changing the path of reactions through enzyme catalysts which these microbes synthesize.

Microbes Rule Our World

There are trillions of microbes which inhabit an adult body. Looking at the sheer numbers, one may think that all these microbes are responsible for the ailments only. But this is not true. On the contrary, microbes are much more our friends than our enemies. Microbes run this world despite their infinitely small size. Their success lies in the sheer numbers and ability to adapt to the changing conditions. Following is the list of some species of the microbes that make our lives better:

Bacillus thuringiensis: A common soil bacterium that is a natural pest-killer in gardens and on crops.

Arbuscular mycorrhizas: It is a fungus living in the soil that helps crops take up nutrients from the soil.

Saccharomyces cerevisiae: Baker’s yeast that makes bread rise by generating carbon dioxide.

Escherichia coli It is one of many kinds of microbes that live in your digestive system to help you digest your food every day.

Streptomyces: Bacteria in soil that makes an antibiotic used to treat infections.

Pseudomonas putida:  It is one of many microbes that clean wastes from sewage water at water treatment plants.

Lactobacillus acidophilus: One of the bacteria that turn milk into yogurt.

There are many other important jobs microbes do. They are used to make medicine. They break down the oil from oil spills which otherwise can pollute the sea and cause havoc to the aquatic life . They make about half of the oxygen we breathe by breaking the water molecules into respective components hydrogen and oxygen. They are the foundation of the food chain that feeds all living things on earth.

We’ve been using microbes for thousands of years to make products we need and enjoy. For example, you can thank fungi for the cheese on your cheeseburger and yeast for your bun. Cheese and bread are two microbe-made foods people have been enjoying since time began.

Over the past 50 years, we’ve begun using microbes to do all kinds of new work for us. Here are some examples of microbes at work in pollution control and medicine.

In pollution control, researchers are using bacteria that eat methane gas to clean up hazardous waste dumps and landfills. These methane-eating bacteria make an enzyme that can break down more than 250 pollutants into harmless cells. By piping methane into the soil, researchers can increase growth of the bacteria that normally live in the polluted soil. More bacteria means faster pollution break up. Also, bacteria is being used as one of the tools to clean up oil spills. These bacteria eat the oil, turning it into carbon dioxide and other harmless by-products.

Fungi and bacteria produce antibiotics such as penicillin and tetracycline . These are medicines we use to fight off harmful bacteria that cause sore throats, ear infections, diarrhea and other discomforts. Scientists have changed the genetic material of bacteria and yeasts to turn them into medicine. They inject genes for medicines they want to make into the microbe cells, as if adding new building information to the microbe’s cell DNA. The scientists then grow the microbes in huge containers called fermenters where they reproduce into billions, all making new medicines.

The Mighty Microbes

Microbes may be very small in size but their sheer numbers and remarkable adaptability to the existing climates is astounding. The word microbe is derived from micro-organisms meaning they are so small that they can be seen with the help of a microscope. But these tiny organisms are so active that they can bring about mammoth changes into the environment in which they live.

When the earth first formed, the atmosphere consisted of carbon dioxide and water. Due to this iron existed in the soluble ionic forms in the water. And also there was organic matter. But in the water lived the earliest bacteria called cyanobacteria which were the first photo synthesizers. They combined carbon dioxide and water using sunlight and turned it into their food. Oxygen was the byproduct of this process. Then why did we said there was no free oxygen in the atmosphere and anaerobic conditions existed. Sure oxygen was produced but hungry sinks for it readily available. Iron in the ionic form immediately captured the produced oxygen and got precipitated and iron ore. Similarly organic matter acquired its share of oxygen.Thus all the iron ore we see on the earth is the handiwork of microbes.

Slowly and slowly, all the available iron was precipitated. Now nothing was there to capture the free oxygen and over the period of time, atmosphere was enriched with oxygen. This free oxygen was poison to many microbes which were adapted to conditions devoid of oxygen. Thus they were exterminated. But as we said in the beginning, some of them got buried deep along with organic matter and survived.

It has been reported that amongst these microbe consortia exist a class which uses carbon dioxide and hydrogen to synthesize methane gas. So far it was thought that methane was produced under aerobic conditions but evidence now indicates to the anaerobic bacteria. These bacteria are the terminal stage actors. Before them are a variety of other bacteria which breakdown the organic matter and provide carbondioxide and hydrogen to these bacteria.

The methane in the gas hydrates which hold the promise to solve the energy requirements of the ever hungry industrial world is formed by these microbes and has been trapped in the ice lattices in the form of clathrate compounds which are nothing but cages formed by the water molecule and methane is trapped inside. These bacteria are thought to be starved for food and are ready to pounce on the reactants as soon as they are available.

Microbes are thus omnipresent and affect the life on our planet since the life began with them.