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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Woogymiogna on January 25, 2019, 12:22:38 AM

Title: Equilibrium problem
Post by: Woogymiogna on January 25, 2019, 12:22:38 AM

Multiple chemistry professionals and others have tried to give me a correct answer to this problem I have come to on the Smartsparrow program for my gen chem 2 class. If anyone can give me an answer it would be appreciated! We've tried everything.

Determine the concentration (in molarity) of H2 at equilibrium, if 0.040 moles of CO and 0.020 moles H2 are placed in a sealed, 10.0-liter container.

CO(g) + 2H2(g)  ::equil:: CH3OH(g)    Kc = 4.3

Title: Re: Equilibrium problem
Post by: Borek on January 25, 2019, 03:01:24 AM

Per forum rules we don't give answers, but we can help you solve the problem. Can you show what you did so far?

Title: Re: Equilibrium problem
Post by: Enthalpy on February 04, 2019, 12:48:01 PM

I just doubt that, under conditions where this equilibrium happens, only CO, H₂ and CH₃OH exist.

Sorry for interrupting.

Title: Re: Equilibrium problem
Post by: AWK on February 04, 2019, 02:27:27 PM

You should set and solve a cubic equation. Its positive root is very small. Show your attempt. Take into account Vidya hint.

Title: Re: Equilibrium problem
Post by: robstamos on February 14, 2019, 05:37:42 PM

I'm stuck on a very similar problem. How do you solve the cubic function in the denominator if you're not able to factor it? Is there some kind of equation to use here?

Title: Re: Equilibrium problem
Post by: AWK on February 14, 2019, 07:06:01 PM

There are few cubic equation calculators online (equation should be in the form AX³ + BX² + CX + D = 0):
eg
solution of the equation
A=-17.2
B=0.1032
C=-1.0001548
D=0.0000000688
is
X1 = 6.878935190739177e-8
X2 = 0.0029999656053240464 + i* 0.24112141065727952
X3 = 0.0029999656053240464 - i* 0.24112141065727952