Faraday

the quantity of charge carried by one mole of electrons (which is approximately equal to Avogadro's constant x the charge on an electron), which has the value 9.6487 x 104 coulombs. It was named after Michael Faraday (1791-1867), a British scientist whose contributions to physics and chemistry include ELECTROMAGNETIC INDUCTION, electrolysis and MAGNETIC FIELDS.

Taken from Dictionary of Science

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Michael Faraday, FRS (22 September 1791 – 25 August 1867) was an English chemist and physicist (or natural philosopher, in the terminology of the time) who contributed to the fields of electromagnetism and electrochemistry.

Faraday studied the magnetic field around a conductor carrying a DC electric current, and established the basis for the electromagnetic field concept in physics. He discovered electromagnetic induction, diamagnetism, and laws of electrolysis. He established thatmagnetism could affect rays of light and that there was an underlying relationship between the two phenomena. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, and it was largely due to his efforts that electricity became viable for use in technology.

As a chemist, Faraday discovered benzene, investigated the clathrate hydrate of chlorine, invented an early form of the bunsen burner and the system of oxidation numbers, and popularized terminology such as anode, cathode, electrode, and ion.

Although Faraday received little formal education and knew little of higher mathematics, such as calculus, he was one of the most influential scientists in history. Some historians of science refer to him as the best experimentalist in the history of science.The SI unit of capacitance, the farad, is named after him, as is the Faraday constant, the charge on a mole of electrons (about 96,485 coulombs). Faraday's law of induction states that a magnetic field changing in time creates a proportional electromotive force.

Faraday was the first and foremost Fullerian Professor of Chemistry at the Royal Institution of Great Britain, a position to which he was appointed for life.

Albert Einstein kept a photograph of Faraday on his study wall alongside pictures of Isaac Newton and James Clerk Maxwell.

Faraday was highly religious; he was a member of the Sandemanian Church, a Christian sect founded in 1730 which demanded total faith and commitment. Biographers have noted that "a strong sense of the unity of God and nature pervaded Faraday's life and work."

Taken from Wikipedia

Joule

the unit for all ENERGY measurements. It is the mechanical equivalent of heat, and one joule (J) is equal to a force of one NEWTON moving one metre, i.e. 1J = 1Nm. It is named after James Prescott Joule (1818-1889), a British physicist who investigated the relationship between mechanical, electrical and heat energy, and, from such investigations, proposed the first law of THERMODYNAMICS, the conservation of energy.

Taken from Dictionary of Science

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The joule (symbol J), named for James Prescott Joule, is the derived unit of energy in the International System of Units. It is the energy exerted by the force of one newton acting to move an object through a distance of one metre. In terms of dimensions:

One joule is defined as the amount of work done by a force of one newton moving an object through a distance of one metre. Other relationships are:

• The work required to move an electric charge of one coulomb through an electrical potential difference of one volt; or one coulomb volt (C·V). This relationship can be used to define the volt;

• The work required to continuously produce one watt of power for one second; or one watt second (W·s) (compare kilowatt hour). This relationship can be used to define the watt.

Taken from Wikipedia

Parabola

a plane curve traced out by a point moving so that its distance from a fixed point (focus) is equal to its perpendicular distance from a fixed straight line (directrix). It is also the curve made by cutting a cone with a flat plane that is parallel to the side of the cone that slopes. Mirrors with a parabolic shape are used in searchlights and telescopes because incoming parallel rays of light are reflectd onto the focus. This property is used in a telescope, and thus the reverse applies in searchlights.

Taken from Dictionary of Science

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In mathematics, the parabola (pronounced /pəˈræbələ/, from the Greek παραβολή) is a conic section, the intersection of a right circular conical surface and a plane parallel to a generating straight line of that surface. Given a point (the focus) and a corresponding line (the directrix) on the plane, the locus of points in that plane that are equidistant from them is a parabola.

The parabola has many important applications, from automobile headlight reflectors to the design of ballistic missiles. They are frequently used in physics, engineering, and many other areas.

Taken from Wikipedia

Lagrangian Points

in particular, with respect to the Earth and Moon, the locations where the gravitational forces are equal and so objects positioned at such points remain fixed. There are five such points between the Earth and Moon.

Taken from Dictionary of Science

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The Lagrangian points (pronounced /ləˈgrandʒiən/; also Lagrange points, L-points, or libration points), are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon). The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to rotate with them. They are analogous to geostationary orbits in that they allow an object to be in a "fixed" position in space rather than an orbit in which its relative position changes continuously.

More technically and precisely, Lagrangian points are the stationary solutions of the circular restricted three-body problem. For example, given two massive bodies in circular orbits around their common center of mass, there are five positions in space where a third body, of comparatively negligible mass, could be placed which would then maintain its position relative to the two massive bodies. As seen in a rotating reference frame with the same period as the two co-orbiting bodies, the gravitational fields of two massive bodies combined with the centrifugal force are in balance at the Lagrangian points, allowing the third body to be stationary with respect to the first two bodies.

Taken from Wikipedia

Identical Twins

two identical individuals which develop from a single fertilized egg that divides early on into two equal parts. Identical twins have the same genetic make up and are always of the same sex.

Taken from Dictionary of Science

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Twins are two offspring resulting from the same pregnancy, usually born in close succession. They can be the same or different sex. Twins can either be monozygotic (MZ, colloquially "identical") or dizygotic (DZ, colloquially "fraternal" or "non-identical").

Taken from Wikipedia

Dalton's Law of Partial Pressures

in a mixture of gases, the total pressure is the sum of the partial pressures of all the gases present. The partial pressure is the pressure a gas in a mixture would exert if it alone occupied the space of volume

Taken from Dictionary of Science

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Dalton's Law of Partial Pressure:

The pressure of a mixture of gases is equal to the sum of the pressures of all of the constituent gases alone.

Mathematically, this can be represented as:

Pressure_Total = Pressure₁ + Pressure₂ ... Pressure_n

Explanation and Discussion:

Dalton's Law explains that the total pressure is equal to the sum of all of the pressures of the parts. This only is absolutely true for ideal gases, but the error is small for real gases. This may at first seem a trivial law, but it can be very valuable in the chemistry lab.

Let's say you want to collect hydrogen gas. To do this, you set up a system that uses a pneumatic trough, a test tube that has a pipetted stopped, a cable that connects the pipett into the pneumatic trough, and a test tube above the cable that collects the hydrogen. Warning: Do not conduct this experiment unless you are under the direction of a chemist or your chemistry teacher. It is dangerous and involves a Bunsen burner and dangerous materials. You submerge the test tube that will collect the hydrogen, and tilt it up so it only contains water. By placing zinc and acid in the pipetted test tube and heating it, hydrogen gas is given off. This gas pumps through the water and enters into the collection test tube. After the first few seconds, the gas will be pure hydrogen. Image of start of hydrogen generation. When the water level is equal in the test tube and the trough, turn off the generator. The pressure inside the test tube will be equal to the atmospheric pressure. Image of pressure equalibrium in hydrogen generator. Now you can use the ideal gas law to determine the number of hydrogen moles in the test tube, right? Not quite.

You see, the water you collected the hydrogen over has vapor pressure that will distort the equation if not accounted for. Because of the Dalton's Law of partial pressure, you know that the pressure in the test tube is from both the hydrogen and the water. To find just the hydrogen, you would have to subtract the vapor pressure of the water. Vapor pressure of water is published in most chemistry books as a table in the appendix, and varies by the temperature of the water.

Calculations with Dalton's Law:

Let's try that last experiment with real numbers. In our lab, the atmospheric pressure is 102.4 kPa. The temperature of our water is 25°C. We used a 250 mL beaker instead of a test tube to collect the hydrogen. Let's find the pressure of the hydrogen, and then find the moles of hydrogen using the ideal gas law.

Step 1: We need to know the vapor pressure of the water. A common table lists the pressure at 25°C as 23.76 torr. A torr is 1 mm of mercury at standard temperature. In kilopascals, that would be 3.17 (1 mm mercury = 7.5 kPa). We should also convert the 250 mL to .250 L and 25°C to 298 L.

Step 2: We can use Dalton's Law to find the hydrogen pressure. It would be:

P_Total = P_Water + P_Hydrogen
102.4 kPa = 3.17 kPa + P_Hydrogen

So the pressure of Hydrogen would be: 99.23 kPa or 99.2 kPa.

Step 3: We use the Ideal Gas Law to get the moles. Recall that the Ideal Gas Law is:

PV=nRT

where P is pressure, V is volume, n is moles, R is the Ideal Gas Constant (0.0821 L-atm/mol-K or 8.31 L-kPa/mol-K), and T is temperature.

Therefore, our equation would be:

99.2 kPa x .250 L = n x 8.31 L-kPa/mol-K x 298 K

This can be re-arranged so:

n = 99.2 kPa x .250 L / 8.31 L-kPa/mol-K / 298 K
n = .0100 mol or 1.00 x 10^-2 mol Hydrogen

Taken from Thinkquest

Oblique Angle

any angle that does not equal 90º (right angle) or any multiple of 90º.

Taken from Dictionary of Science