concentration

(kŏn'sən-trā'shən)

1. 1. The act or process of concentrating, especially the fixing of close, undivided attention.
   2. The condition of being concentrated.
2. Something that has been concentrated.
3. Chemistry. The amount of a specified substance in a unit amount of another substance.

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In communications, the combining of multiple channels into one.

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1. Condition of a bank's loan portfolio measured by the number of loans extended to a particular industry. Excessive lending to a single industry (agriculture, oil and gas exploration, real estate) indicates a lack of Diversification in the loan portfolio, and potential credit risk. Many Texas and Oklahoma banks suffered enormous losses in the mid-1980s when the oil exploration industry bottomed out; many were later taken over by other banks. In general, most banks report loan concentrations above 50% of equity. The Securities and Exchange Commission requires banks to disclose in financial reports any concentration exceeding 10% of loans. See also Asset Quality; Liquidity.

2. Share of deposits owned by a bank in a given market. The U.S. Department of Justice uses a statistical yardstick, the Herfindahl Index, in gauging the anticompetitive effects of bank mergers. The index is calculated by adding the market shares of a product, such as deposits, owned by banks in a market and squaring the results. The index indicates both the number of firms in a market and their relative size. For example, a market with five firms, each having individual market shares of 30, 20, 20, 20, and 10 percent would have an index of 2200. Generally, the Justice Department will not challenge a merger unless the post-merger index is at least 1800 and the merger causes an increase of at least 200 on the scale.

The ability to sustain attention and to focus on particular target stimuli. Concentration is an important skill for most sports activities. It can be learned and improved by specific training. Footballers and hockey players, for instance, play distraction games in which one person has to try to concentrate on performing a skill while others try to distract him or her.

A wide range of factors can affect concentration. Eating a heavy meal, very high levels of noise, and anxiety can reduce concentration. The morning is the best time to concentrate on complex tasks which rely on memory (see circadian rhythm). It is difficult to sustain concentration at any time on tasks that are too simple, too complicated, or too repetitive.

noun

1. A converging at a common center: confluence, conflux, convergence. See edge/center.
2. Concentration of the mental powers on something: attention, attentiveness, consideration, heedfulness, regardfulness. See excite/bore/interest.

Definition: aggregation
Antonyms: dispersal, scattering, separation

n. 1. an assembly of troops in a given area.

2. the simultaneous firing of a number of artillery pieces or mortars on a common, usually prearranged, area or target.

See the Introduction, Abbreviations and Pronunciation for further details.

The ability to focus attention on selected stimuli. Concentration involves the ability to become totally absorbed in the present moment, for example, of a competition or athletic performance, and to focus attention on relevant stimuli and ignore irrelevant stimuli. Concentration is important in all athletic performances. It is a skill that can be improved by specific training (see concentration training).

Quotes:

"It's shocking how little there is to do with tennis when you're just thinking about nothing except winning every point." - Andre Agassi

"Concentrate, play your game, and don't be afraid to win." - Amy Alcott

"Concentrate; put all your eggs in one basket, and watch that basket..." - Andrew Carnegie

"Concentration is my motto -- first honesty, then industry, then concentration." - Andrew Carnegie

"By concentrating our attention on the effect rather than the causes, we can avoid the laborious, nearly impossible task of trying to detect and deflect the many psychological influences on liking." - Robert Cialdini

"I never could have done what I have done without the habits of punctuality, order, and diligence, without the determination to concentrate myself on one subject at a time..." - Charles Dickens

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1. Any of several methods to increase the strength of a material. Concentrated fruit juices are an example of products using this approach.
   
2. The degree of strength. A dilution of ethyl acetate that is 10 parts ester and 90 parts alcohol has a concentration of 10%
   

1. 
   (a) mass concentration or mass density symbol: ρ or γ an SI derived physical quantity; it equals the mass of a specified component per unit volume of the system in which it is contained. It is expressed in kg m⁻³.
   
   (b) amount-of-substance concentration or amount concentration or (in clinical chemistry) substance concentration symbol: c; an SI derived physical quantity; it equals the number of moles of a specified component per unit volume of the system in which it is contained. Where there is no risk of confusion the term concentration may be used alone. It is expressed in mol m⁻³ or mol dm⁻³. Amount concentration continues to be expressed often in terms of the litre (symbol: l or L), which is not an SI unit, although 1 L = 1 dm³. The older, non-SI, term molarity is still commonly used for this quantity; a solution of, say, 1 mol dm⁻³ concentration may thus be referred to also as a 1 molar solution or denoted a 1 M solution, where M is treated as a symbol for mol dm⁻³ (or mol L⁻¹). See molar (def. 2).
   
   (c) surface concentration symbol: Γ an SI derived physical quantity; it equals the number of moles of a specified substance per unit area of the surface at which it is present. It is expressed in mol m⁻².
   
   (d) number concentration or number density symbol: C or (sometimes) n; an SI derived physical quantity; it equals the number of specified particles or molecular entities per unit volume of the system in which it is contained. It is expressed in m⁻³. Note: The concentration of a solute in solution may sometimes be expressed in more convenient units esp. in a percentage; e.g. (for solids) as the mass of solute in grams per 100 millilitres of solution (abbr.: % w/v), or (for liquids) as the number of volumes of solute per 100 volumes of solution (abbr.: % v/v). See also activity (def. 3), molality, osmolality, osmolarity.
   
2. the act or process of concentrating. See concentrate (def. 1, 2).

1. increase in strength by evaporation.
2. the ratio of the mass or volume of a solute to the mass or volume of the solution or solvent.

• hydrogen ion c. — an expression of the degree of acidity or alkalinity (pH) of a solution. See also acid–base balance.
• mass c. — the mass of a constituent substance divided by the volume of the mixture, as milligrams per liter (mg/l).
• minimum effective c. — the threshold level of a drug in plasma below which the efficiency of the drug as a treatment drops off sharply.
• molar c. — the amount of a constituent in moles (millimoles or micromoles) divided by the volume of the mixture, as millimoles per liter (mmol/l).
• c. test — a test of renal function based on the patient's ability to concentrate urine. See water deprivation test.

• Physical Properties and Changes - concentration: amount of solute per unit of solvent in a solution
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For other uses, see Concentration (disambiguation).

In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Furthermore, in chemistry, four types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration.^[1] The term concentration can be applied to any kind of chemical mixture, but most frequently it refers to solutes in solutions.

Contents 1 Qualitative description 2 Quantitative notation 2.1 Mass concentration 2.2 Molar concentration 2.3 Number concentration 2.4 Volume concentration 3 Related quantities 3.1 Normality 3.2 Molality 3.3 Mole fraction 3.4 Mole ratio 3.5 Mass fraction 3.6 Mass ratio 4 Dependence on volume 5 Table of concentrations and related quantities 6 See also 7 References

Qualitative description

These glasses containing red dye demonstrate qualitative changes in concentration. The solutions on the left are more dilute, compared to the more concentrated solutions on the right.

Often in informal, non-technical language, concentration is described in a qualitative way, through the use of adjectives such as "dilute" for solutions of relatively low concentration and "concentrated" for solutions of relatively high concentration. To concentrate a solution, one must add more solute (for example, alcohol), or reduce the amount of solvent (for example, water). By contrast, to dilute a solution, one must add more solvent, or reduce the amount of solute. Unless two substances are fully miscible there exists a concentration at which no further solute will dissolve in a solution. At this point, the solution is said to be saturated. If additional solute is added to a saturated solution, it will not dissolve, except in certain circumstances, when supersaturation may occur. Instead, phase separation will occur, leading to coexisting phases, either completely separated or mixed as a suspension. The point of saturation depends on many variables such as ambient temperature and the precise chemical nature of the solvent and solute.

Quantitative notation

There are four quantities that describe concentration:

Mass concentration

Main article: Mass concentration (chemistry)

The mass concentration ρ_i is defined as the mass of a constituent m_i divided by the volume of the mixture V:

The SI-unit is kg/m³.

Molar concentration

Main article: Molar concentration

The molar concentration c_i is defined as the amount of a constituent n_i divided by the volume of the mixture V:

The SI-unit is mol/m³. However, more commonly the unit mol/L (= mol/dm³) is used.

Number concentration

Main article: Number concentration

The number concentration C_i is defined as the number of entities of a constituent N_i in a mixture divided by the volume of the mixture V:

The SI-unit is 1/m³.

Volume concentration

Main article: Volume concentration

The volume concentration ϕ_i (also called volume fraction) is defined as the volume of a constituent V_i divided by the volume of all constituents of the mixture V prior to mixing:

The SI-unit is m³/m³.

Related quantities

Several other quantities can be used to describe the composition of a mixture. Note that these should not be called concentrations.

Normality

Main article: Normality (chemistry)

Normality is defined as the molar concentration c_i divided by an equivalence factor f_eq. Since the definition of the equivalence factor may not be unequivocal, IUPAC and NIST discourage the use of normality.

Molality

Main article: Molality

(Not to be confused with Molarity)

The molality of a solution b_i is defined as the amount of a constituent n_i divided by the mass of the solvent m_solvent (not the mass of the solution):

The SI-unit for molality is mol/kg.

Mole fraction

Main article: Mole fraction

The mole fraction x_i is defined as the amount of a constituent n_i divided by the total amount of all constituents in a mixture n_tot:

The SI-unit is mol/mol. However, the deprecated parts-per notation is often used to describe small mole fractions.

Mole ratio

Main article: Mixing ratio

The mole ratio r_i is defined as the amount of a constituent n_i divided by the total amount of all other constituents in a mixture:

If n_i is much smaller than n_tot, the mole ratio is almost identical to the mole fraction.

The SI-unit is mol/mol. However, the deprecated parts-per notation is often used to describe small mole ratios.

Mass fraction

Main article: Mass fraction (chemistry)

The mass fraction w_i is the fraction of one substance with mass m_i to the mass of the total mixture m_tot, defined as:

The SI-unit is kg/kg. However, the deprecated parts-per notation is often used to describe small mass fractions.

Mass ratio

Main article: Mixing ratio

The mass ratio ζ_i is defined as the mass of a constituent m_i divided by the total mass of all other constituents in a mixture:

If m_i is much smaller than m_tot, the mass ratio is almost identical to the mass fraction.

The SI-unit is kg/kg. However, the deprecated parts-per notation is often used to describe small mass ratios.

Dependence on volume

Concentration depends on the variation of the volume of the solution due mainly to thermal expansion.

Table of concentrations and related quantities

Concentration type	Symbol	Definition	SI-unit	other unit(s)
mass concentration	ρi or γi	mi / V	kg/m3	g/100mL (=g/dL)
molar concentration	ci	ni / V	mol/m3	M (=mol/L)
number concentration	Ci	Ni / V	1/m3	1/cm3
volume concentration	ϕi	Vi / V	m3/m3
Related quantities	Symbol	Definition	SI-unit	other unit(s)
normality		ci / feq	mol/m3	N (=mol/L)
molality	bi	ni / msolvent	mol/kg
mole fraction	xi	ni / ntot	mol/mol	ppm, ppb, ppt
mole ratio	ri	ni / (ntot − ni)	mol/mol	ppm, ppb, ppt
mass fraction	wi	mi / mtot	kg/kg	ppm, ppb, ppt
mass ratio	ζi	mi / (mtot − mi)	kg/kg	ppm, ppb, ppt

See also

• Serial dilution
• Dose concentration

References

1. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "concentration".

v d e Articles related to solutions Solution Ideal solution · Aqueous solution · Solid solution · Buffer solution · Flory-Huggins · Mixture · Suspension · Colloid · Phase diagram · Eutectic point · Alloy · Saturation · Supersaturation · Serial dilution · Dilution (equation) · Apparent molar property Concentration and related quantities Molar concentration · Mass concentration · Number concentration · Volume concentration · Normality · Percentage solution · Molality · Mole fraction · Mass fraction · Mixing ratio Solubility Solubility equilibrium · Total dissolved solids · Solvation · Solvation shell  · Enthalpy of solution · Lattice energy · Raoult's law · Henry's law · Solubility table (data) · Solubility chart Solvent (category) · Acid dissociation constant · Protic solvent · Inorganic nonaqueous solvent · Solvation · List of boiling and freezing information of solvents Partition coefficient · Polarity · Hydrophobe · Hydrophile · Lipophilic · Amphiphile

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Dansk (Danish)
n. - koncentration, sammenslutning

idioms:

• concentration camp    koncentrationslejr

Nederlands (Dutch)
concentratie

Français (French)
n. - concentration sur, spécialisation, (Chim) concentration

idioms:

• concentration camp    camp de concentration

Deutsch (German)
n. - Konzentration, Ansammlung

idioms:

• concentration camp    Konzentrationslager

Ελληνική (Greek)
n. - συγκέντρωση, αυτοσυγκέντρωση, συμπύκνωμα, συμπυκνωμένη ουσία ή μάζα, (χημ.) περιεκτικότητα ή σθένος, (για ορυκτά κ.λπ.) εμπλουτισμός
attrib. - συγκέντρωσης

idioms:

• concentration camp    στρατόπεδο συγκεντρώσεως

Italiano (Italian)
concentrazione

idioms:

• concentration camp    campo di concentramento

Português (Portuguese)
n. - concentração (f)
attrib. - qualidade de quem se concentra

idioms:

• concentration camp    campo (m) de concentração

Русский (Russian)
сосредоточенность, концентрация

idioms:

• concentration camp    концентрационный лагерь

Español (Spanish)
n. - concentración, mitin, densidad

idioms:

• concentration camp    campo de concentración

Svenska (Swedish)
n. - koncentration, anrikning (tekn.)
attr. - koncentrations-

中文（简体）(Chinese (Simplified))
集中, 专心, 集合

idioms:

• concentration camp    集中营

中文（繁體）(Chinese (Traditional))
n. - 集中, 專心, 集合

idioms:

• concentration camp    集中營

한국어 (Korean)
n. - 전념, 농도, 집중강의

日本語 (Japanese)
n. - 集中, 専念, 集結, 濃縮, 濃度

idioms:

• concentration camp    強制収容所

العربيه (Arabic)
‏(الاسم) تركيز, حشد (صفه)‏

עברית (Hebrew)
n. - ‮התרכזות, ריכוז‬

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