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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: leena on June 17, 2009, 07:51:52 AM

Title: What is a chemical equivalent?
Post by: leena on June 17, 2009, 07:51:52 AM

According to Faraday's 2^nd law(I think),when the same current passes through a series of electrolytic solutions,the mass ratio is equal to the ratio of their chemical equivalents(hope I'm right?)
I googled for the definition of chemical equivalent or E,
E = atomic mass unit(amu)/valency,was the given definition.  Now I learnt in school,that E=Relative molecular mass(RMM) /valency.
This may seem like a very basic question but,it's very vital I understand,
 how is the amu = RMM???
I know that amu = 1/12th the mass of an atom of C -12 isotope ,so how is this equal to the RMM.?
and my other question based on E is ,
Is the chemical equivalent of an atom say H = chemical equivalent of a molecule,say H₂?
Please help.

Title: Re: What is a chemical equivalent?
Post by: Borek on June 17, 2009, 08:04:53 AM

Quote from: leena on June 17, 2009, 07:51:52 AM

E = atomic mass unit(amu)/valency,was the given definition.

You must have read it wrong, are you sure it was not mass EXPRESSED in amu divided by valency and taken in grams?

Title: Re: What is a chemical equivalent?
Post by: leena on June 18, 2009, 05:23:49 AM

Thanks.
Yes ,I may have read it wrong,though I can't seem to find the link that I referred,I found a new one,
http://encyclopedia2.thefreedictionary.com/equivalent+weight (http://encyclopedia2.thefreedictionary.com/equivalent+weight)
http://www.physchem.co.za/OB12-che/electrolysis.htm#faraday (http://www.physchem.co.za/OB12-che/electrolysis.htm#faraday)

It says that E= (atomic weight or the formula weight)/valence?

Quote

Is the chemical equivalent of an atom say H = chemical equivalent of a molecule,say H2?

So would the E for H2 be = 2/2? and E for H atom will also be= 1/1?
Thank you