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Chemical equation for glucose osazone and limiting reactants

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IBY
#1
Oct1-09, 03:02 PM
P: 107
1. The problem statement, all variables and given/known data

Okay, a while ago, I did a lab that had me get glucose osazone (C18-H22-N4-O4). Now, I am trying to calculate the theoretical mass of the osazone. The chemical equations goes as follows:

C6-H5-N2-H3*HCl + Na-C2-H3-O2*H2-O ------> C6-H5-N2-H3 + H-C2-H3-O2 + Na-Cl + 3(H2-O)

After that:
C6-H12-O6 + 3(C6-H5-N2-H3) --------> C18-H22-N4-O4 + C6-H5-N-H2 + N-H3 + 2(H2-O)

I found the limiting reactants in the first equation for Phenylhydrazine (C6-H5-N2-H3), but the thing is, in the second equation, 2 mols of phenylhydrazine gets used for osazone (C18-H22-N4-O4) and water, and the third mole decomposes into the ammonia (N-H3) and aniline (C6-H5-N-H2). So the part I am having trouble is, should I use the ration 2:1 from phenylhydrazine to osazone or keep the 3:1 ration in order to find the theoretical yield?
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chemisttree
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Oct2-09, 11:08 AM
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Quote Quote by IBY View Post
1. The problem statement, all variables and given/known data

Okay, a while ago, I did a lab that had me get glucose osazone (C18-H22-N4-O4). Now, I am trying to calculate the theoretical mass of the osazone. The chemical equations goes as follows:

C6-H5-N2-H3*HCl + Na-C2-H3-O2*H2-O ------> C6-H5-N2-H3 + H-C2-H3-O2 + Na-Cl + 3(H2-O)

After that:
C6-H12-O6 + 3(C6-H5-N2-H3) --------> C18-H22-N4-O4 + C6-H5-N-H2 + N-H3 + 2(H2-O)

I found the limiting reactants in the first equation for Phenylhydrazine (C6-H5-N2-H3), but the thing is, in the second equation, 2 mols of phenylhydrazine gets used for osazone (C18-H22-N4-O4) and water, and the third mole decomposes into the ammonia (N-H3) and aniline (C6-H5-N-H2). So the part I am having trouble is, should I use the ration 2:1 from phenylhydrazine to osazone or keep the 3:1 ration in order to find the theoretical yield?
If instead of making the phenylhydrazine you used, you obtained it from a bottle... which ratio would you use?

Remember that the first reaction is essentially a neutralization reaction... the phenylhydrazine hydrochloride is free-based with sodium acetate. If I discover a way to do this that requires 20 moles of the the hydrochloride to my newly-discovered base (capable of neutralizing 20 moles of the hydrochloride!), will we all have to go back and rewrite every paper ever published that used sodium acetate for the job?


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