Equivalent weight: Difference between revisions

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No such term exists in chemistry. Whoever created this page must have confused weight with mass. Please delete this entry, and see "equivalent mass."

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 {{wiktionary|equivalent weight}}
+No such term exists in chemistry. Whoever created this page must have confused weight with mass. Please delete this entry, and see "equivalent mass."
-Equivalent weight is the amount of an element that reacts, or is involved in reaction with, 1 [[Mole (unit)|mole]] of electrons. It is 'defined' by many texts as the weight of the element combining with 1 g hydrogen, 8 g oxygen or 35.5 g chlorine, each of which would either provide or accept one mole of electrons in a reaction.  This concept is very useful in [[gravimetric analysis|gravimetric]] and [[volumetric analysis]].
-When choosing [[primary standard]]s in [[analytical chemistry]], compounds with higher equivalent weights are generally more desirable because weighing errors are reduced or minimized.
-For example, [[hydrogen]], with atomic weight 1.008 and valence 1, has an equivalent weight of 1.008. [[Oxygen]] assumes a valence of 2 and has an atomic weight of 15.9994, so it has an equivalent weight of 7.9997.
-Elements may assume different equivalent weights in different compounds.  For example, [[iron]] (atomic weight 55.845) assumes equivalent weight 27.9225 if it is valence 2 in the compound (ferrous); or 18.615 if it is valence 3 (ferric).
-The equivalent weight can also be computed for other than pure elements.  For example, the [[carbonate]] radical (CO<sub>3</sub><sup>2-</sup>) has a formula (atomic) weight of 60.0092 and assumes valence 2 in compounds, so its equivalent weight is 30.0046.
-The equivalent weight of a substance may be defined as that weight of it which will react with or produce one mole of hydrogen. (Or 1g of H since 1mol H=1g H)
-'''Equivalent weight in Polymer Chemistry''' signifies the amount of reactive functional groups on the [[polymer chain]] . Its value denotes gram solid resin that includes one mole of functional reactive group attached to the polymer backbone.
-It is widely used to indicate the reactivity of [[polyol]], [[isocyanate]], or [[epoxy]] [[thermoset]] resins which would undergo [[crosslinking]] reactions through those functional groups. The formula to calculate the equivalent weight of particular functional reactive groups is as follows;
-% Functional reactive group (FRG) = (gr of FRG)/(100gr resin)*100
-Equivalent Weight = (MW of FRG)/(% FRG) * 100
-'''ex''': For an acrylic polyol resin, MW of -OH=17;
-% -OH = (gr of -OH)/(100gr acrylic resin)*100
-Equivalent weight of -OH = 17/(%-OH)*100
-[[Category:Stoichiometry]]
-[[Category:Amount of substance]]
-[[Category:Polymer chemistry]]
-[[fr:Équivalent (chimie)]]
-[[is:Jafngild þyngd]]
-[[it:Peso equivalente]]
-[[tr:Eşdeğer ağırlık]]
-[[uk:Хімічний еквівалент]]