Dilution is the process of decreasing the concentration of a

solute In chemistry, a solution is defined by IUPAC as "A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are ...

in a

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Solu ...

, usually simply by mixing with more

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

like adding more water to the solution. To dilute a solution means to add more solvent without the addition of more solute. The resulting solution is thoroughly mixed so as to ensure that all parts of the solution are identical. The same direct relationship applies to gases and

vapor In physics, a vapor (American English) or vapour (Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature,R ...

s diluted in air for example. Although, thorough mixing of gases and vapors may not be as easily accomplished. For example, if there are 10 grams of

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

(the solute) dissolved in 1

litre The litre ( Commonwealth spelling) or liter ( American spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metres (m3). A ...

of water (the solvent), this solution has a certain salt concentration (

molarity Molar concentration (also called molarity, amount concentration or substance concentration) is the number of moles of solute per liter of solution. Specifically, It is a measure of the concentration of a chemical species, in particular, of a solu ...

). If one adds 1 litre of water to this solution, the salt concentration is reduced. The diluted solution still contains 10 grams of salt (0.171 moles of

NaCl Sodium chloride , commonly known as edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral hali ...

). Mathematically this relationship can be shown by

equation In mathematics, an equation is a mathematical formula that expresses the equality of two expressions, by connecting them with the equals sign . The word ''equation'' and its cognates in other languages may have subtly different meanings; for ...

c_1 V_1 = c_2 V_2

where *''c''₁ = initial concentration or molarity *''V''₁ = initial volume *''c''₂ = final concentration or molarity *''V''₂ = final volume ....

Basic room purge equation

The basic room purge equation is used in

industrial hygiene Occupational hygiene or industrial hygiene (IH) is the anticipation, recognition, evaluation, control, and confirmation (ARECC) of protection from risks associated with exposures to hazards in, or arising from, the workplace that may result in ...

. It determines the time required to reduce a known vapor concentration existing in a closed space to a lower vapor concentration. The equation can only be applied when the purged volume of vapor or gas is replaced with "clean" air or gas. For example, the equation can be used to calculate the time required at a certain ventilation rate to reduce a high

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

concentration in a room.

D_t=\left \frac \right \cdot \ln \left \frac\right

Sometimes the equation is also written as:

\quad = \frac \cdot (t_\text - t_\text)

where

t_\text = 0

*''D_t'' = time required; the unit of time used is the same as is used for ''Q'' *''V'' = air or gas volume of the closed space or room in cubic feet, cubic metres or

s *''Q'' = ventilation rate into or out of the room in

cubic feet per minute The cubic foot (symbol ft3 or cu ft)
, . is an Cubic metre per second, litres per second *''C''_initial = initial concentration of a vapor inside the room measured in ppm *''C''_final = final reduced concentration of the vapor inside the room in ppm

Dilution ventilation equation

The basic room purge equation can be used only for purge scenarios. In a scenario where a liquid continuously evaporates from a container in a ventilated room, a differential equation has to be used:

\frac = \frac

where the ventilation rate has been adjusted by a mixing factor ''K'':

Q' = \frac

*''C'' = concentration of a gas *''G'' = generation rate *''V'' = room volume *''Q''′ = adjusted ventilation rate of the volume

Dilution in welding

The dilution in welding terms is defined as the weight of the base metal melted divided by the total weight of the weld metal. For example, if we have a dilution of 0.40, the fraction of the weld metal that came from the consumable electrode is 0.60.

References

External links

* http://pubs.acs.org/doi/abs/10.1021/ja01320a004
Easy dilution calculator
{{DEFAULTSORT:Dilution (Equation) Equations Separation processes

Basic room purge equation

Dilution ventilation equation

Dilution in welding

See also

References

External links