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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Problem of the Week Archive => Topic started by: Borek on May 21, 2012, 06:19:57 AM

Title: Problem of the week - 21/05/2012
Post by: Borek on May 21, 2012, 06:19:57 AM
Another (simple) one taken from the old publication:

Gaseous mixture contained 51.3% (v/v) of H2S, the rest was CO2. 1750 mL of the mixture (measured at 760 mm Hg and 21 °C) was heated to 350 °C, cooled, and pumped through a CaCl2, increasing its mass by 34.7 mg. What is the equilibrium constant of the carbonyl sulfide synthesis from H2S and CO2 at 350 °C?
Title: Re: Problem of the week - 21/05/2012
Post by: sjb on May 26, 2012, 10:14:07 AM
Quote from: Borek on May 21, 2012, 06:19:57 AM
Another (simple) one taken from the old publication:

Gaseous mixture contained 51.3% (v/v) of H2S, the rest was CO2. 1750 mL of the mixture (measured at 760 mm Hg and 21 °C) was heated to 350 °C, cooled, and pumped through a CaCl2, increasing its mass by 34.7 mg. What is the equilibrium constant of the carbonyl sulfide synthesis from H2S and CO2 at 350 °C?

OK, here's a start

CO2 + H2S  ::equil:: COS + H2O

CaCl2  :rarrow: CaCl2.6H2O (not sure of the exact formula of the hydrate, could be di, or tetra? May be irrelevant)

34.7 mg increase in the weight of CaCl2, means (34.7 x 10-3/18.02) mol of water.
Title: Re: Problem of the week - 21/05/2012
Post by: Rutherford on May 26, 2012, 11:24:10 AM
I got 3.062*10-3.
Title: Re: Problem of the week - 21/05/2012
Post by: Borek on May 26, 2012, 04:10:53 PM
Close, but not perfect.
Title: Re: Problem of the week - 21/05/2012
Post by: Sophia7X on May 26, 2012, 05:19:39 PM
0.00282?
Title: Re: Problem of the week - 21/05/2012
Post by: Borek on May 26, 2012, 05:26:03 PM
Raderford was closer.
Title: Re: Problem of the week - 21/05/2012
Post by: Rutherford on May 27, 2012, 04:09:24 AM
Done more precisely and got that k=3.1507*10-3.
Title: Re: Problem of the week - 21/05/2012
Post by: Borek on May 27, 2012, 04:26:20 AM
3.15×10-3 it is  :)

Compare E. Terres, H. Wesemann, Angew.Chem. 45, 795 (1932).