Finding out unknown compound in the solution and boiling point of the solution

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Dhamnekar Winod
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Finding out unknown compound in the solution and boiling point of the solution

Post by Dhamnekar Winod »

After a sample of compound X weighing 1.286 g was dissolved in 25 g of C6H6, the freezing point of the resulting solution was found to be 3.27℃.

What is the molecular weight of compound X? What is the name of solute compound? What is the boiling point of the solution?

My answer:

Molecular weight of compound is 118 g. The boiling point of the solution is 81.255℃.

Are these answer correct? I don't know the name of the compound.
Last edited by Dhamnekar Winod on Thu Apr 22, 2021 7:54 am, edited 3 times in total.
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Re: Finding out unknown compound/element in the solution and boiling point of the solution

Post by ChenBeier »

Dont think so, how you can dissolve tin in benzene?
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Dhamnekar Winod
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Re: Finding out unknown compound/element in the solution and boiling point of the solution

Post by Dhamnekar Winod »

I am wrong. I modified wrongly the original question given by authors. Now I corrected the question and answer. You may check it now.
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Re: Finding out unknown compound/element in the solution and boiling point of the solution

Post by ChenBeier »

You didn't show your calculation.
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Dhamnekar Winod
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Re: Finding out unknown compound in the solution and boiling point of the solution

Post by Dhamnekar Winod »

We know that 1.286 g of the compound are dissolved in 25 g benzene, and therefore in 1000 g of benzene, there are\(1.286 \times \frac{1000}{25}=51.44 g, \Delta T_{fp} = 5.50^\circ -3.27^\circ =2.23^\circ C; \Delta T_{fp} = K_{fp}\cdot m; m=\frac{\Delta T_{fp}}{K_{fp}}=\frac{2.23}{5.12}=0.436 m; \frac{51.44 g}{0.436 mol}= 118 g/mol\)

where,

\(\Delta T_{fp}=\) change in temperature of the solution. m= molality of the solution.
\( K_{fp}=\)molal freezing point constant for benzene

What would be a name of the compound?
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Re: Finding out unknown compound in the solution and boiling point of the solution

Post by ChenBeier »

Calculation is ok.
But without more information it is impossible to find out which compound it is.
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Re: Finding out unknown compound in the solution and boiling point of the solution

Post by Dhamnekar Winod »

I think computed boiling point of the solution 81.255℃ is correct.
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Re: Finding out unknown compound in the solution and boiling point of the solution

Post by ChenBeier »

Yes its correct. But cannot say which compound it is. For this need more analysis, like NMR , IR, UV/ Vis spectra and elementar analysis of C, H, N,O, maybe Halogen.
As suggested it cannot be a metal like tin.
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