Thursday, 26 October 2017

9 Importance of Sound & Its Role in Our Life

Sound is a form of energy which trans-locates through matter.

This matter includes air, water and solid matter.

Without matter there is no sound propagation. This sound has energy and is directly dependent on it.

To produce a sound one needs energy and but is not a viable form like photons of light.

This sound propagates in the form of waves through air.

These waves have frequency and wavelength as measurable parameters.

The sound quality largely varies due to these two parameters.

For humans and animals this sound is useful in one or other way and has great importance.

Importance of sound human life

1. For communication: Sound is the only main form of communication for animals while it is the key for humans communicate with spoken languages besides body languages.

Animals communicate in their own language of sounds by moan, cry, weep etc.

Without sound, voice would have been difficult to be emitted out.

For humans, this voice communication expands to telephonic (distant communication) means by using mobiles and phones.

The communication is understood by ears through hearing, auditory words, expressive tone etc. One can express feeling just by sound variation even.

2. Signalling system: Sound is the signalling system used for trains, automobiles, river flows (Dam water release), industry sirens.

Sound as a signalling system is used as horns, sirens, calling bells, beeps etc. Sound signal system is one of the least expensive ones. Further it is less harmful to the environment around. But excess and frequent use can cause sound pollution.

Further alarm system uses sound. Hence a mobile ringing, alarms, message alerts use sound as alerting means.

3. Echo system: Echo is a reflection of sound arriving back to the point of emission. We can notice echo when we make a notice in an empty building or well or even boot sounds of army march. Echo is a type of sound resonance. It is very much useful in music.

4. For music: Music is the art which relies solely on sound. Without sound there is no music from music systems. Music communicates message, soothes the mind and also helps relieve stress.

Music is a sound in a controlled and fine tuned manner. Music relies a lot on frequency and pitch of the voice.

For instruments the factors like the frequency, intensity and also the resonance of the sound matter. Hence you can notice for instruments like violin, guitar there is a big hallow at the end. This hallow creates resonance of sound making the music further distinct to the instrument.

This is music is now a day recorded for future use by sound reproduction systems.

5. For finding the depth/ distant objects: This you might have come across in physics. Sound waves are one of the few means available to measure the depth of the seas and also the deep holes in the earth. Also other objects at a long distance can be found by SONAR waves i.e SOUND NAVIGATION AND RANGING. The sound is allowed to travel through the sea or ocean bed and return back. This time taken by particular frequency of sound to reach the sea bed and return back to the source or absorber (receiver of sound) is used to calculate the depth of the sea.

Similarly a moving object can send sound waves in the direction of its motion and know if any there are any objects moving in at long distances.

6. For degassing of liquids: Liquids like water and solvents used in analysis have air and other gases entrapped inside them. This air has to be removed for proper flow through minute pores in the matter. This is particularly required for chromatography experiments. The procedure to remove gas from the solvent is called degassing of solvents. This is essential for proper analysis of compounds using HPLC (high performance liquid chromatography) or else it can slow down the pressure in the column and hinder analysis.

7. For de-granulation of solid particles: Large solid particle in a suspension or tissues fraction can be broken down by grinding. But very small particles like less than 1mm or so cannot be broken down further using grinders. Then they can be broken down by use of ultrasonic sound waves. These waves are thought to create vigorous crests and troughs in the liquid media. These crests and troughs bring about splitting of particles to smaller ones.

8. Telephone communication: Telephone is one of the best discoveries ever made by man. The telephone machine receives sound waves from the person at mouth piece. The sound waves cause vibration in carbon particles in it. Thus the electric signal is generated based on the pitch and frequency of voice and is communicated. Here the sound from the voice exerts pressure on the diaphragm in the mouth piece.

This is the procedure followed to break suspension to nano particle size for better use. The apparatus used for this purpose is called sonicator.

9. In sterilization: Ultra sound is also tried in sterilization. This is done to inhibit growth of microbes and even kill them.

Sonication disrupts the cell wall of bacteria and kill them. But they are not highly lethal but are used in combination with disinfectants for synergistic effect.

10. To enhance cell growth: Sonication is also found to be effective in tissue culture. Some findings suggest that use of sonication selectively enhances the growth of cells & tissues. Also it is found to facilitate gene transfer during tissue culture & in biotechnology. refer.

2 Comments

Syrain

This isn’t actually uses of sound, it is what sound does. Rethink your priorities

Reply
- joke
  
  why dont you try to do
  
  Reply

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Sunday, 15 October 2017

ATOMIC STRUCTURE IMAGE

Friday, 13 October 2017

BOHR MODEL

Bohr model

From Wikipedia, the free encyclopedia

The Bohr model of the hydrogen atom (Z = 1) or a hydrogen-like ion (Z > 1), where the negatively- charged electron confined to an atomic shell encircles a small, positively charged atomic nucleus and where an electron jumps between orbits it is accompanied by an emitted or absorbed amount of electromagnetic energy (hν).^[1] The orbits in which the electron may travel are shown as grey circles; their radius increases as n², where n is the principal quantum number. The 3 → 2 transition depicted here produces the first line of the Balmer series, and for hydrogen (Z = 1) it results in a photon of wavelength 656 nm (red light).

In atomic physics, the Rutherford–Bohr model or Bohr model or Bohr diagram, introduced by Niels Bohr and Ernest Rutherford in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar to structure of the Solar System, but with attraction provided by electrostatic forces rather than gravity. After the cubic model (1902), the plum-pudding model (1904), the Saturnian model (1904), and the Rutherford model (1911) came the Rutherford–Bohr model or just Bohr model for short (1913). The improvement to the Rutherford model is mostly a quantum physical interpretation of it. The model's key success lay in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen. While the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced. Not only did the Bohr model explain the reason for the structure of the Rydberg formula, it also provided a justification for its empirical results in terms of fundamental physical constants.
The Bohr model is a relatively primitive model of the hydrogen atom, compared to the valence shell atom. As a theory, it can be derived as a first-order approximation of the hydrogen atom using the broader and much more accurate quantum mechanics and thus may be considered to be an obsolete scientific theory. However, because of its simplicity, and its correct results for selected systems (see below for application), the Bohr model is still commonly taught to introduce students to quantum mechanics or energy level diagrams before moving on to the more accurate, but more complex, valence shell atom. A related model was originally proposed by Arthur Erich Haas in 1910, but was rejected. The quantum theory of the period between Planck's discovery of the quantum (1900) and the advent of a full-blown quantum mechanics (1925) is often referred to as the old quantum theory.

protons

Proton

From Wikipedia, the free encyclopedia

Proton
The quark content of a proton. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.
Classification	Baryon
Composition	2 up quarks, 1 down quark
Statistics	Fermionic
Interactions	Gravity, electromagnetic, weak, strong
Symbol	p , p+, N+
Antiparticle	Antiproton
Theorized	William Prout (1815)
Discovered	Eugen Goldstein (1886) and Ernest Rutherford (1917–1919, named by him, 1920)
Mass	1.672621898(21)×10⁻²⁷ kg^[1] 938.2720813(58) MeV/c²^[2] 1.007276466879(91) u^[2]
Mean lifetime	> 2.1×10²⁹ years (stable)
Electric charge	+1 e 1.6021766208(98)×10⁻¹⁹ C^[2]
Charge radius	0.8751(61) fm^[2]
Electric dipole moment	< 5.4×10⁻²⁴ e⋅cm
Electric polarizability	1.20(6)×10⁻³ fm³
Magnetic moment	1.4106067873(97)×10⁻²⁶ J⋅T⁻¹^[2] 1.5210322053(46)×10⁻³ μ_B^[2] 2.7928473508(85) μ_N^[2]
Magnetic polarizability	1.9(5)×10⁻⁴ fm³
Spin	1/2
Isospin	1/2
Parity	+1
Condensed	I(J^P) = 1/2(1/2⁺)

A proton is a subatomic particle, symbol
p
or
p+, with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as "nucleons".
One or more protons are present in the nucleus of every atom; they are a necessary part of the nucleus. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol Z). Since each element has a unique number of protons, each element has its own unique atomic number.
The word proton is Greek for "first", and this name was given to the hydrogen nucleus by Ernest Rutherford in 1920. In previous years, Rutherford had discovered that the hydrogen nucleus (known to be the lightest nucleus) could be extracted from the nuclei of nitrogen by atomic collisions. Protons were therefore a candidate to be a fundamental particle, and hence a building block of nitrogen and all other heavier atomic nuclei.
In the modern Standard Model of particle physics, protons are hadrons, and like neutrons, the other nucleon (particles present in atomic nuclei), are composed of three quarks. Although protons were originally considered fundamental or elementary particles, they are now known to be composed of three valence quarks: two up quarks and one down quark. The rest masses of quarks contribute only about 1% of a proton's mass, however.^[3] The remainder of a proton's mass is due to quantum chromodynamics binding energy, which includes the kinetic energy of the quarks and the energy of the gluon fields that bind the quarks together. Because protons are not fundamental particles, they possess a physical size, though not a definite one; the root mean square charge radius of a proton is about 0.84–0.87 fm or 0.84×10⁻¹⁵ to 0.87×10⁻¹⁵ m.^[4]^[5]
At sufficiently low temperatures, free protons will bind to electrons. However, the character of such bound protons does not change, and they remain protons. A fast proton moving through matter will slow by interactions with electrons and nuclei, until it is captured by the electron cloud of an atom. The result is a protonated atom, which is a chemical compound of hydrogen. In vacuum, when free electrons are present, a sufficiently slow proton may pick up a single free electron, becoming a neutral hydrogen atom, which is chemically a free radical. Such "free hydrogen atoms" tend to react chemically with many other types of atoms at sufficiently low energies. When free hydrogen atoms react with each other, they form neutral hydrogen molecules (H₂), which are the most common molecular component of molecular clouds in interstellar space.

ionic bonding

Ionic bonding

From Wikipedia, the free encyclopedia

Sodium and fluorine undergoing a redox reaction to form sodium fluoride. Sodium loses its outer electron to give it a stable electron configuration, and this electron enters the fluorine atom exothermically. The oppositely charged ions – typically a great many of them – are then attracted to each other to form a solid.

Ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. The ions are atoms that have gained one or more electrons (known as anions, which are negatively charged) and atoms that have lost one or more electrons (known as cations, which are positively charged). This transfer of electrons is known as electrovalence in contrast to covalence. In the simplest case, the cation is a metal atom and the anion is a nonmetal atom, but these ions can be of a more complex nature, e.g. molecular ions like NH₄⁺ or SO₄²⁻. In simpler words, an ionic bond is the transfer of electrons from a metal to a non-metal in order to obtain a full valence shell for both atoms.
It is important to recognize that clean ionic bonding – in which one atom or molecule completely share an electron from another^{[clarification needed]} – cannot exist: all ionic compounds have some degree of covalent bonding, or electron sharing. Thus, the term "ionic bonding" is given when the ionic character is greater than the covalent character – that is, a bond in which a large electronegativity difference exists between the two atoms, causing the bonding to be more polar (ionic) than in covalent bonding where electrons are shared more equally. Bonds with partially ionic and partially covalent character are called polar covalent bonds.
Ionic compounds conduct electricity when molten or in solution, typically as a solid. Ionic compounds generally have a high melting point, depending on the charge of the ions they consist of. The higher the charges the stronger the cohesive forces and the higher the melting point. They also tend to be soluble in water. Here, the opposite trend roughly holds: the weaker the cohesive forces, the greater the solubility.

Thursday, 12 October 2017

chemical equvation

Chemical equation

From Wikipedia, the free encyclopedia

This article relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources. (September 2011)

A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae, wherein the reactant entities are given on the left-hand side and the product entities on the right-hand side.^[1] The coefficients next to the symbols and formulae of entities are the absolute values of the stoichiometric numbers. The first chemical equation was diagrammed by Jean Beguin in 1615.^[2]

Formation of chemical reaction

A chemical equation consists of the chemical formulas of the reactants (the starting substances) and the chemical formula of the products (substances formed in the chemical reaction). The two are separated by an arrow symbol (

\rightarrow

, usually read as "yields") and each individual substance's chemical formula is separated from others by a plus sign.
As an example, the equation for the reaction of hydrochloric acid with sodium can be denoted:

2 HCl + 2 Na → 2 NaCl + H
2

This equation would be read as "two HCl plus two Na yields two NaCl and H two." But, for equations involving complex chemicals, rather than reading the letter and its subscript, the chemical formulas are read using IUPAC nomenclature. Using IUPAC nomenclature, this equation would be read as "hydrochloric acid plus sodium yields sodium chloride and hydrogen gas."
This equation indicates that sodium and HCl react to form NaCl and H₂. It also indicates that two sodium molecules are required for every two hydrochloric acid molecules and the reaction will form two sodium chloride molecules and one diatomic molecule of hydrogen gas molecule for every two hydrochloric acid and two sodium molecules that react. The stoichiometric coefficients (the numbers in front of the chemical formulas) result from the law of conservation of mass and the law of conservation of charge (see "Balancing Chemical Equation" section below for more information).

Common symbols

Symbols are used to differentiate between different types of reactions. To denote the type of reaction:^[1]

" $=$ " symbol is used to denote a stoichiometric relation.
" $\rightarrow$ " symbol is used to denote a net forward reaction.
" $\rightleftarrows$ " symbol is used to denote a reaction in both directions.
" $\rightleftharpoons$ " symbol is used to denote an equilibrium.

The physical state of chemicals is also very commonly stated in parentheses after the chemical symbol, especially for ionic reactions. When stating physical state, (s) denotes a solid, (l) denotes a liquid, (g) denotes a gas and (aq) denotes an aqueous solution.
If the reaction requires energy, it is indicated above the arrow. A capital Greek letter delta (

\Delta

) is put on the reaction arrow to show that energy in the form of heat is added to the reaction.

h\nu

is used if the energy is added in the form of light. Other symbols are used for other specific types of energy or radiation.

Balancing chemical equations

As seen from the equation CH
4 + 2 O
2 → CO
2 + 2 H
2O, a coefficient of 2 must be placed before the oxygen gas on the reactants side and before the water on the products side in order for, as per the law of conservation of mass, the quantity of each element does not change during the reaction

P₄O₁₀ + 6 H₂O → 4 H₃PO₄
This chemical equation is being balanced by first multiplying H₃PO₄ by four to match the number of P atoms, and then multiplying H₂O by six to match the numbers of H and O atoms.

The law of conservation of mass dictates that the quantity of each element does not change in a chemical reaction. Thus, each side of the chemical equation must represent the same quantity of any particular element. Likewise, the charge is conserved in a chemical reaction. Therefore, the same charge must be present on both sides of the balanced equation.
One balances a chemical equation by changing the scalar number for each chemical formula. Simple chemical equations can be balanced by inspection, that is, by trial and error. Another technique involves solving a system of linear equations.
Balanced equations are written with smallest whole-number coefficients. If there is no coefficient before a chemical formula, the coefficient 1 is understood.
The method of inspection can be outlined as putting a coefficient of 1 in front of the most complex chemical formula and putting the other coefficients before everything else such that both sides of the arrows have the same number of each atom. If any fractional coefficient exists, multiply every coefficient with the smallest number required to make them whole, typically the denominator of the fractional coefficient for a reaction with a single fractional coefficient.
As an example, seen in the above image, the burning of methane would be balanced by putting a coefficient of 1 before the CH₄:

1 CH₄ + O₂ → CO₂ + H₂O

Since there is one carbon on each side of the arrow, the first atom (carbon) is balanced.
Looking at the next atom (hydrogen), the right-hand side has two atoms, while the left-hand side has four. To balance the hydrogens, 2 goes in front of the H₂O, which yields:

1 CH₄ + O₂ → CO₂ + 2 H₂O

Inspection of the last atom to be balanced (oxygen) shows that the right-hand side has four atoms, while the left-hand side has two. It can be balanced by putting a 2 before O₂, giving the balanced equation:

CH₄ + 2 O₂ → CO₂ + 2 H₂O

This equation does not have any coefficients in front of CH₄ and CO₂, since a coefficient of 1 is dropped.

Matrix Method

Generally, any chemical equation involving J different molecules can be written as:

\sum _{j=1}^{J}\nu _{j}R_{j}=0

where R_j is the symbol for the j-th molecule, and ν_j is the stoichiometric coefficient for the j-th molecule, positive for products, negative for reactants (or vice-versa). A properly balanced chemical equation will then obey:

\sum _{j=1}^{J}a_{ij}\nu _{j}=0

where the composition matrix a_ij is the number of atoms of element i in molecule j. Any vector which, when operated upon by the composition matrix yields a zero vector, is said to be a member of the kernel or null space of the operator. Any member ν_j of the null space of a_ij will serve to balance a chemical equation involving the set of J molecules comprising the system. A "preferred" stoichiometric vector is one for which all of its elements can converted to integers with no common divisors by multiplication by a suitable constant.
Generally, the composition matrix is degenerate: That is to say, not all of its rows will be linearly independent. In other words, the rank (J_R) of the composition matrix is generally less than its number of columns (J). By the rank-nullity theorem, the null space of a_ij will have J-J_R dimensions and this number is called the nullity (J_N) of a_ij. The problem of balancing a chemical equation then becomes the problem of determining the J_N-dimensional null space of the composition matrix. It is important to note that only for J_N=1, will there be a unique solution. For J_N>1 there will be an infinite number of solutions to the balancing problem, but only J_N of them will be independent: If J_N independent solutions to the balancing problem can be found, then any other solution will be a linear combination of these solutions. If J_N=0, there will be no solution to the balancing problem.
Techniques have been developed ^[3]^[4] to quickly calculate a set of J_N independent solutions to the balancing problem and are superior to the inspection and algebraic method in that they are determinative and yield all solutions to the balancing problem.

Ionic equations

An ionic equation is a chemical equation in which electrolytes are written as dissociated ions. Ionic equations are used for single and double displacement reactions that occur in aqueous solutions.
For example, in the following precipitation reaction:

{\ce {{CaCl2}+2AgNO3->{Ca(NO3)2}+2AgCl(v)}}

the full ionic equation is:

{\ce {{Ca^{2+}}+{2Cl^{-}}+{2Ag+}+2NO3^{-}->{Ca^{2+}}+{2NO3^{-}}+2AgCl(v)}}

In this reaction, the Ca²⁺ and the NO₃⁻ ions remain in solution and are not part of the reaction. That is, these ions are identical on both the reactant and product side of the chemical equation. Because such ions do not participate in the reaction, they are called spectator ions. A net ionic equation is the full ionic equation from which the spectator ions have been removed. The net ionic equation of the proceeding reactions is:

{\ce {{2Cl^{-}}+2Ag+->2AgCl(v)}}

or, in reduced balanced form,

{\ce {{Ag+}+Cl^{-}->AgCl(v)}}

In a neutralization or acid/base reaction, the net ionic equation will usually be:

H⁺(aq) + OH⁻(aq) → H₂O(l)

There are a few acid/base reactions that produce a precipitate in addition to the water molecule shown above. An example is the reaction of barium hydroxide with phosphoric acid, which produces not only water but also the insoluble salt barium phosphate. In this reaction, there are no spectator ions, so the net ionic equation is the same as the full ionic equation.

{\ce {{3Ba(OH)2}+2H3PO4->{6H2O}+Ba3(PO4)2(v)}}

{\ce {{3Ba2+}+{6OH^{-}}+{6H+}+2PO4^{3-}->{6H2O}+Ba3(PO4)2(v)}}

Double displacement reactions that feature a carbonate reacting with an acid have the net ionic equation:

{\ce {{2H+}+CO3^{2-}->{H2O}+CO2\uparrow }}

If every ion is a "spectator ion" then there was no reaction, and the net ionic equation is null.
Generally, if z_j is the multiple of elementary charge on the j-th molecule, charge neutrality may be written as:

\sum _{j=1}^{J}z_{j}\nu _{j}=0

where the ν_j are the stoichiometric coefficients described above. The z_j may be incorporated^[3]^[5] as an additional row in the a_ij matrix described above, and a properly balanced ionic equation will then also obey:

\sum _{j=1}^{J}a_{ij}\nu _{j}=0

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Thursday, 26 October 2017