New Year! Time to attend year ending and year starting :)

GLOBAL WARMING......a serious thing to consider...

The sudden rise in the average temperature results in global warming and this is the main outline demanding attention. The augmentation in temperature is owing to the carbon dioxide increase in the atmosphere in combination with other greenhouse gases such as methane, aerosols and nitrous oxide. The earth is habitable when there are normal gases in balance. But, when the same normal gases reach more than the average levels, it is tough to be eliminated and results in global warming. The temperatures start rising in the ocean and the air.
Global warming pollution

Global temperature increase shifts the ecosystems to the extent that glaciers retreat, plant productivity changes, water supply alters and the fragile ecosystems are destroyed. The effects overall are irreparable. Global warming pollution refers to more than glaciers and polar bears. Scientists estimate the water levels to be declining and the lakes to become warmer.

Global warming pollution enhances problems owing to extra warm atmosphere. The carbon dioxide gases absorb the sunlight and avert the heat from entering space and thereby cause the additional warmth in water and air. Ice and snow melting also has gained speed and ultimately compounds to global warming issues.

Greenhouse gases

Home is found to be mainly responsible to contribute maximum carbon dioxide in the atmosphere and to increase greenhouse gases. Today, everyone depends on energy and reverting to Stone Age cannot be given a thought. Though, it seriously looks like we will be forced to return to Atone Age if the fossil fuels are used exorbitantly.

Burning fossil fuels escalate the atmospheric gases. Agriculture and land clearing activities also imbalances the atmospheric gases. Recently, global warming has shown steep increase due to human activities. It is estimated that nearly 82% of energy related carbon dioxide emission is owing to natural gas and petroleum and subsequently the increase is found in greenhouse gases.

Clean technologies

Clean technologies making less use of energy is highly recommended. Homes should make use of pollution free energies to have a decrease in the exhaustion of carbon dioxide gas into the atmosphere. This will help in decreasing global warming problem to a great extent. Greenhouse effect is only due to global warming resulting by affecting everyone on the earth. Even turning a light or watching TV releases carbon dioxide gases compounding to more global warming problems.

You can find a rapid change in the planets. Home, being the major contributor for global warming, it is best to make at least small efforts to decrease the usage of electricity. This will reduce the carbon dioxide gases exhaustion. Clean technologies are the best alternatives to bring effective changes in reducing global warming pollution, protecting ecosystems, wildlife, biodiversity and also in improving the quality of air.

Simple alternative steps

Simple alternative steps help in improving healthy surrounding. The simple steps include clean car technology. This meant the pollution is less and the car becomes more efficient by offering more mileage. You can use clean fuels, maintain regularly and upgrade the vehicle to be more fuel efficient and also reduce global warming.

Simple alternative steps are easily done by transforming the house hold lights to energy saving bulbs. Throwing trash should be stopped and given for recycling. Similarly, walking instead of driving vehicles prevents global warming. This also keeps your body fit. Conversely, planting more trees supports the reduction of global warming.

JET ENGINE

What is a jet engine?

A jet engine is a machine for turning fuel into thrust (forward motion). The thrust is produced by action and reaction—a piece of physics also known as Newton's third law of motion. The force (action) of the exhaust gases pushing backward produces an equal and opposite force (reaction) called thrust that powers the vehicle forward. Exactly the same principle pushes a skateboard forward when you kick backward with your foot. In a jet engine, it's the exhaust gas that provides the "kick".

Melde's experiment is a scientific experiment carried out by the German physicist Franz Melde on the standing waves produced in a tense cable originally set oscillating by a tuning fork, later improved with connection to an electric vibrator. This experiment attempted to demonstrate that mechanical waves undergo interference phenomena. In the experiment, mechanical waves traveled in opposite directions from immobile points, called nodes. These waves were called standing waves by Melde since the position of the nodes and loops (points where the cord vibrated) stayed static.

Traditional day

Construction, Working and Limitations of Hydrogen Electrode

chemistry-assignment:(Q.2)

This is a gas electrode. It consists of a thin rectangular platinum foil which is coated with fresh platinum black to increase the adsorption capacity of the metal. This is welded and the end of it is fused into the inner tube through the base. In the inner tube, little mercury is taken and a Cu wire is introduced to make the external electrical contact. The inner tube is enclosed in an outer jacket having an inlet tube for sending in H₂ gas and has a perforated wider base for the escape of excess of H₂. This unit is dipped in HCl taken in a beaker such that the metal foil remains in the solution.

Working

When pure and dry H₂ gas is passed through the inlet tube, a part of the gas gets adsorbed and the excess bubbles out through the perforations. Between the H₂ gas absorbed on the surface of the metal and H⁺ of the solution, an equilibrium is established and an electrical double layer of opposite charges is formed. The potential developed is called H₂ electrode potential.

In the above system, when the H₂ gas at a pressure of 1atm is bubbled through 1M HCl, the electrode (constructed) or formed is called STANDARD HYDROGEN ELECTRODE (SHE) or Normal H₂ electrode (NHE). This is represented as Pt, H₂ / H⁺(760 mm of Hg) (IM)

The standard H₂ electrode potential is defined as the potential that is developed between the H₂ gas adsorbed on the pt metal and H⁺ of the solution when the H₂ gas at a pressure of 760 mm of Hg is in equilibrium with H⁺ of unit concentration

The magnitude of SHE potential is considered to be zero. It is used-

1) For the determination of electrode potential of metal electrode system.

2) For the determination of pH of the solution.

Limitations

1) It is rather difficult to regulate the pressure of the H₂ gas to be at exactly 1atm throughout the experiment.

2) Excess of H₂ bubbling out carries little HCl with it and hence the H⁺ concentration decreases. In such a system, it is difficult to maintain the concentration of HCl at 1M.

3) Platinum foil gets easily poisoned by the impurities present in the gas and HCl. In fact, the attainment of equilibrium is ensured by trial and error.

4) If the solution contains any oxidizing agent, the H₂ electrode cannot be used.

Determination of Single Electrode Potential

chemistry-assignment:(Q.1)

It is not possible to measure directly the potential developed at interface of the metal gas and its ions in solution using voltmeter. Hence the electrode whose single electrode potential has to be determined is coupled with another electrode of known potential and the emf of the cell is determined by the potentiometeric method.

Normally SHE is used for coupling and in the electrochemical cell constructed, it acts either as a positive or negative electrode depending on the nature of the other electrode.

When SHE acts as positive electrode, then,

E.m.f = E^+ve - E^-ve

This means when the electrode potential is negative with respect to SHE, oxidation takes place at that electrode.

When SHE acts as negative electrode, then,

Emf = E^+ve - E^-ve

This means when the electrode potential is positive reduction takes place at the metal electrode.

Example:

electrode a cell made of a Zn electrode immersed in 1M ZnSO₄ is coupled with a S.H.E. The E.M.F. of the above cell is 0.76V. The direction of flow indicates that oxidation takes place so a standard reduction potential of -0.76V is given to it.