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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: charzhino on January 25, 2012, 04:33:10 AM

Title: Moles/Mass initiator calculation check
Post by: charzhino on January 25, 2012, 04:33:10 AM
Could someone please check if this calculation is correct? I am trying to find how much nitrogen is released when the initiator Vazo 68 (below) is decomposed. I am using 0.1g of it.

 I have done moles = mass / mR   therefore  moles = 0.1/280(mR of vazo 68) = 3.57x10-4.

This is the number of moles of Vazo that will be decomposed. Therefore the mass of nitrogen is equal to moles x mR of nitrogen.  

3.57x10-4 x 28 = 0.01g

Is this correct? I feel I need to put the avagadros number in somewhere but not sure. Thanks

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Title: Re: Moles/Mass initiator calculation check
Post by: UG on January 25, 2012, 03:53:44 PM
Quote from: charzhino on January 25, 2012, 04:33:10 AM
This is the number of moles of Vazo that will be decomposed. Therefore the mass of nitrogen is equal to moles x mR of nitrogen.   

3.57x10-4 x 28 = 0.01g
But is there not 4 nitrogen atoms per molecule of the initiator? Doesn't that mean that 2 molecules of N2 will be produced when 1 molecule of the initiator decomposes? You just need to make this slight adjustment, no need for Avogadro's number, unless you want to work out the total number of atoms of nitrogen formed.
Title: Re: Moles/Mass initiator calculation check
Post by: DrCMS on January 26, 2012, 04:19:27 AM
Quote from: UG on January 25, 2012, 03:53:44 PM
Quote from: charzhino on January 25, 2012, 04:33:10 AM
This is the number of moles of Vazo that will be decomposed. Therefore the mass of nitrogen is equal to moles x mR of nitrogen.   

3.57x10-4 x 28 = 0.01g
But is there not 4 nitrogen atoms per molecule of the initiator? Doesn't that mean that 2 molecules of N2 will be produced when 1 molecule of the initiator decomposes? You just need to make this slight adjustment, no need for Avogadro's number, unless you want to work out the total number of atoms of nitrogen formed.

Do not jump in to give opinions on subjects you clearly do not understand. 

These type of azo initiators decompose to give two radicals and one nitrogen molecule.
http://en.wikipedia.org/wiki/Radical_initiator

The radicals are then used to start a polymerisation reaction.
Title: Re: Moles/Mass initiator calculation check
Post by: UG on January 26, 2012, 04:39:11 AM
Oh ok, sorry I had no idea.
Title: Re: Moles/Mass initiator calculation check
Post by: DrCMS on January 26, 2012, 05:56:57 AM
The thing that most annoys me on this board is people giving bad advice based on too little knowledge.  In acedemia that is a bad thing in industry it can be fatal and I mean that literally. 

Go look at the CSB website http://www.csb.gov/default.aspx and see how many deaths in the chemical industry have been caused by bad advice and poor judgement. 

Synthron http://www.csb.gov/investigations/detail.aspx?SID=17&Type=2&pg=1&F_All=y
T2 http://www.csb.gov/investigations/detail.aspx?SID=8&Type=2&pg=1&F_All=y
MFG http://www.csb.gov/investigations/detail.aspx?SID=29&Type=2&pg=1&F_All=y
Morton http://www.csb.gov/investigations/detail.aspx?SID=53&Type=2&pg=1&F_All=y

are prime examples of people with a little bit of knowledge being very dangerous indeed.