Calculating the Reaction Quotient

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Nathaniel 2E
Posts: 27
Joined: Mon Jun 25, 2018 3:00 am

Calculating the Reaction Quotient

Postby Nathaniel 2E » Wed Jan 09, 2019 9:14 pm

Calculate the reaction quotient, QC, from the following equilibrium data collected in a 3.00 L sealed reaction vessel for the reaction: AsH3 (g) ⇌ As (s) + H2 (g)
AsH3 = 5.55 x 10-4 mol, As = 3.31 x 10-3 mol, H2 = 1.23 x 10-3 mol.

This is from the second module, I keep messing up and not arriving at the right answer. Do I use the QC equation of Products/Reactants? Do I have to convert these moles in to something else? Is the solid, As, a part of the calculation?

Kim Tran 1J
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

Re: Calculating the Reaction Quotient

Postby Kim Tran 1J » Wed Jan 09, 2019 9:18 pm

Yes, you would use the QC equation.

Since the problem only gives you moles and the equilibrium constant equation uses concentration (i.e. molarity which is mol/L), you would need to divide the given moles by 3.00 L in order to be able to calculate the QC.

And you would not include the solid as a part o your QC equation. When calculating the equilibrium constant, you do not include solids and liquids.

Your answer should be 2.01 x 10^-3

Margaret Akey
Posts: 80
Joined: Fri Sep 28, 2018 12:18 am

Re: Calculating the Reaction Quotient

Postby Margaret Akey » Wed Jan 09, 2019 9:30 pm

Don't forget to balance your chemical equation!

Selina Bellin 2B
Posts: 62
Joined: Fri Sep 28, 2018 12:25 am

Re: Calculating the Reaction Quotient

Postby Selina Bellin 2B » Wed Jan 09, 2019 10:17 pm

yes, divide mol by L to get molarity/concentration, no solids or liquids in calculating this


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