Phases and Reaction Quotient (HW)

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Sophia Diaz - Dis 1B
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Phases and Reaction Quotient (HW)

Postby Sophia Diaz - Dis 1B » Sat Jan 12, 2019 7:10 pm

In homework problem 11.13 (6th edition):

Write the reaction quotient for:
P4210(s) + 16 H2O (l) --> 4H3PO4(aq) + 10 H2S (aq)

The answer is:

Q = (H3PO4)^4 (H2S)^10

I don't think I understand why we don't include the molecules in liquid or solid form. Why do we only include molecules in a gas or aqueous phase?

julia_lok_2K
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Joined: Fri Sep 28, 2018 12:25 am

Re: Phases and Reaction Quotient (HW)

Postby julia_lok_2K » Sat Jan 12, 2019 7:26 pm

It's because the concentrations of solids and liquids do not change during the reactions, so it is kind of pointless to consider solids and liquids for equilibrium.

AnnaYan_1l
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Re: Phases and Reaction Quotient (HW)

Postby AnnaYan_1l » Sat Jan 12, 2019 11:05 pm

Molar concentrations of a pure substance (solid or liquid) does not change in a reaction. Therefore, solids and liquids are not included in the expression.

Nicklas_Wright_1A
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Re: Phases and Reaction Quotient (HW)

Postby Nicklas_Wright_1A » Sun Jan 13, 2019 4:10 pm

You can think of the solid ad liquid concentrations as being factored out and included in K.


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