# 0.4 Gram equivalent concept  (Page 2/4)

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## Equivalent weight of a base

The valence factor of a base is equal to its acidity. The acidity of a base is equal to furnishable hydroxyl ion (OH-) in its aqueous solution. With this background, we define equivalent weight of a base as :

$\text{Equivalent weight},E=\frac{\text{Molecular weight of base}}{\text{Acidity}}$

Acidity of KOH is 1, whereas acidity of $Ca{\left(OH\right)}_{2}$ is 2. Hence, equivalent weight of KOH is (39 + 16 + 1)/1 = 56/1 = 56. Similarly, equivalent weight of $Ca{\left(OH\right)}_{2}$ is {40 + 2X(16+1)}/2 = 74/2=37.

## Equivalent weight of a compound

The valence factor of a compound depends on the manner a compound is involved in a reaction. The compounds of alkali metal salts and alkaline earth metal salts are, however, constant. These compounds are ionic and they dissociate in ionic components in aqueous solution. In this case, valence factor is equal to numbers of electronic charge on either cation or anion.

$\text{Equivalent weight},E=\frac{\text{Molecular weight of compound}}{\text{Numbers of electronic charge on cation or anion}}$

The numbers of electronic charge on cation of $NaHC{O}_{3}$ is 1. Hence, equivalent weight of $NaHC{O}_{3}$ is (23 + 1 + 12 + 3X16)/1 = 84.

If we look at the defining ratio of equivalent weight of a compound (AB) formed of two radicals (say A and B), then we can rearrange the ratio as :

$\text{Equivalent weight, E}=\frac{\text{Molecular weight of Radical A}}{\text{Numbers of electronic charge}}+\frac{\text{Molecular weight of Radical B}}{\text{Numbers of electronic charge}}$

Thus,

$⇒\text{Equivalent weight of AB}=\text{Equivalent weight of A}+\text{Equivalent weight of B}$

## Equivalent weight of an ion

The valence factor of an ion is equal to numbers of electronic charge on the ion. Therefore, we define equivalent weight of an ion as :

$\text{Equivalent weight},E=\frac{\text{Molecular weight of ion}}{\text{Numbers of electronic charge}}$

The numbers of electronic charge on carbonate ion ( $C{O}_{3}^{2-}$ ) is 2. Hence, equivalent weight of carbonate ion is (12 + 3X16)/1 = 60/2 = 30. Similarly, equivalent weight of aluminum ion ( $A{l}^{3+}$ ) is 27/3 = 9.

## Equivalent weight of an oxidizing or reducing agent

In a redox reaction, one of the reacting entities is oxidizing agent (OA). The other entity is reducing agent (RA). The oxidizer is recipient of electrons, whereas reducer is releaser of electrons. The valence factor for either an oxidizing or reducing agent is equal to the numbers of electrons transferred from one entity to another.

$\text{Equivalent weight},E=\frac{\text{Molecular weight of compound}}{\text{Numbers of electrons transferred in redox reaction}}$

Alternatively,

$\text{Equivalent weight},E=\frac{\text{Molecular weight of compound}}{\text{Change in oxidation number in redox reaction}}$

Potassium dichromate in acidic medium is a strong oxidizer. It means it gains electrons during redox reaction. Potassium dichromate in acidic solution results in :

${K}_{2}C{r}_{2}{O}_{7}+14{H}^{+}+6{e}^{-}\to 2{K}^{+}+2C{r}^{3+}+7{H}_{2}O$

$\text{Equivalent weight of}\phantom{\rule{1em}{0ex}}{K}_{2}C{r}_{2}{O}_{7}=\frac{294.2}{6}=49$

Study of redox reaction is in itself an exclusive and extensive topic. We shall, therefore, discuss redox reaction separately.

## Gram equivalent(geq)

It is equal to mass in grams numerically equal to equivalent weight. If the mass of a chemical entity is “g” grams, then the given mass contains gram equivalents given by :

can someone help me with some logarithmic and exponential equations.
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
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Sherica
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Sherica
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Tamia
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a perfect square v²+2v+_
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algebra 2 Inequalities:If equation 2 = 0 it is an open set?
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
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yes
Asali
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what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
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Porter
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Yasmin
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
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Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
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Prasenjit
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Damian
silver nanoparticles could handle the job?
Damian
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Azam
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At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
how did you get the value of 2000N.What calculations are needed to arrive at it
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