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using the Le Chatlier’s principle and determine the higher boiling point

Submitted by rocktown1990 on Mon, 04/16/2012 - 23:36

 

Please Help with the following 
 
CH3COOH(l) + SOCl2(l) ⇌ CH3COCl(l) + SO2(g) + HCl(g)
 
a. Use Le Chatlier’s principle to determine which reaction vessel would yield more product:  a 100 mL 
sealed and evacuated flask, or a 500 mL sealed and evacuated flask (assume the liquids only take 
up about 50 mL of volume).
 
 
b. Which compound (CH3COOH or CH3COCl) has a higher boiling point, and why? 

The forward reaction is accompanied by an increase in pressure as gases are made from liquid. To favour products you want the reaction to take place in as large a volume as possible as pressure increases will be less. So 500mL. This assumes you use the same quantiies of reactants in each case.

In the second there will be dipole to diole attraction between both molecules. However, in the acetic acid, there are hydrogen bonds which are stronger. So ethanoic acid. This actually exists as dimers with the attractions between the double bonded O atom and the H of the -OH group of the other molecule.

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The 500 mL flask would provide a greater amount of product.  The reaction will procede to the right initially until the system reaches equilibrium.  The concentrations (or pressure ) of the HCl in both flasks would be the same at equilibrium, the larger flask would hold a greater mass of HCl.

 

I would predict the acetic acid would have the higher boiling point due to the presence of hydrogen bonding between its molecules.