THE REDOX REACTION

The reduction-oxidation reaction pervades all chemistry and biology. The name is nothing to do with actual reaction process. Oxidation is the loss of electrons from the molecules and the reduction is the gain of electrons by the molecules.

An example : We have seen festival fire works. The festival crackers contains magnesium. When the Mg is lit up, it burns brightly. Here Mg reacts with atmospheric oxygen and produce magnesium oxide (MgO2). Mg lost two negative electrons(oxidation) and oxygen gained the same 2 electrons (reduction). Hence, positive ions of magnesium forms bond with negative oxygen ions. Also energy is released as heat and light. Here the 'Oxidation" name is justified. Whenever there is oxidation, reduction must also accompany it.

There are many examples for 'Redox' reaction like, extracting iron from ore; corrosion; combustion in vehicles; photosynthesis; respiration; metabolism; etc.

Today, we highly depend on batteries. We use heavy lead-acid batteries in all the vehicles. Lap-top, mobiles and tablets work using light lithium -ion batteries. Redox reaction is the main stay of these batteries.

In chemical batteries, the oxidation and reduction reaction are spatially separated. At negative electrode, electrons are released (oxidation) and at the positive electrode, electrons are absorbed and utilized in reduction reaction. When the two electrodes are connected, electrons will flow from negative end to positive end and the reactions are completed. So the electric current is established.

Lead acid battery -working:
At the negative plate, lead reacts with sulfuric acid and forms lead sulfate and releases two electrons.
Then the electrons flow to other end.
At positive plate, lead oxide reacts with sulfuric acid and produces lead sulfate + water. Here the two electrons utilized.

If you send the current through the battery, reverse reaction takes place. That is what we call 'charging' and it is also basis for the electrolysis process.
The redox reactions keep our gadgets and ourselves alive.

Note: Cut an apple. keep the two halves in open air. the color changes to brownish yellow. The redox reaction takes place due to oxygen in the air.

Comments

LISSAJOUS FIGURES

Definition: "When a particle is subjected to two sine wave motion or two oscillatory motion at right angles, the particle describes lissajous figures". We know sine wave motion and circular motion is basically same. Hence we draw two circles A and B perpendicular to each other. The circle B rotates twice faster than circle A. That is, frequency of circle B is two times than that of A. A particle at the intersection of two circles is subjected to two sine wave motion A and B at 90 degree simultaneously. The particle will describe figures depending on the frequency and phase of A and B . In our case, the ratio of frequency is 1:2 and the two waves are in phase. To draw lissajous figures : A moving point in both the circles are chosen. Here we should remember; during the time taken by the circle A to complete one rotation, circle B completes two. Hence the points are marked on the circles according to their speed. Then straight lines

THE PARABOLA

A jet of water shooting from a hose pipe will follow a parabolic path. What is the so special about parabola. Y= x^2 Draw a graph for the above equation. It will result in a parabola. This parabola is also called unit parabola. Any equation involving square will yield a parabola. Example: Y = 2x^2 +3x+3 (also called quadratic equation) X= 2 and -2, both satisfies the equation 4 = X^2. Parabolic equations always have two solutions. Any motion taking place freely under gravity follows parabolic path. Examples: An object dropped from a moving train, A bomb dropped from flying plane, A ball kicked upwards. If a beam of light rays fall on the parabolic shaped mirror, they will be reflected and brought to focus on a point. This fact is made use of in Dish Antenna, Telescope mirrors, etc. Inverted parabola shape is used in the construction of buildings and bridges. Because the shape is able to bear more weight. A plane

CASINO'S GAME

Let us find out how the casino survives with mathematics. Say, your friend invite you for a game of dice. You must bet (wager) 2 dollars. If you roll 'six' you will get back 8 dollars. The game will go on for 30 rounds. All sounds good. The probability of rolling 'six' is 1/6. Since the game will be played for 30 times, the 'expected win' is 30*1/6 = 5. That is, you are expected to win 5 rounds out of 30. Hence your gain will be 5 * 8 =40 dollars. ok. This also implies that you will loose 25 rounds. Hence your loss will be 25*2 =50 dollars. Your net gain will be gain-less = 40-50 = -10 dollars. For 30 rounds, the loss is -10 dollars, Hence, for one round =-10/30 = -1/3 dollars. There will be a loss of -1/3 or 0.33 dollars per round. It is not a fair game. Let us make a simple formula to calculate 'Pay out per round\. The probability for a win = p The pay-out in case of win = V No. of rounds = n The expect

sciencecapsules

Search This Blog