Constants in Q Equation
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Constants in Q Equation
How can we determine when a term in the equation for Q would be equal to the value of 1?
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Re: Constants in Q Equation
Hi, this is the guide I use to determine when a term in the equation for the reaction quotient (Q) would be equal to 1:
For gaseous reactions or reactions in aqueous solutions:
If the concentration of a product is equal to the concentration of the corresponding reactant, the term for that species in the reaction quotient equation is 1.
For heterogeneous reactions involving solids or pure liquids:
Terms involving concentrations of solids or pure liquids are treated as constants and are equal to 1.
At equilibrium:
All terms in the reaction quotient equation (except for solids and pure liquids) are equal to their equilibrium concentrations or pressures, resulting in Q = K (the equilibrium constant).
During the reaction:
If the reaction is not at equilibrium, terms in the reaction quotient equation differ from 1, indicating that the reaction has not yet reached equilibrium.
For gaseous reactions or reactions in aqueous solutions:
If the concentration of a product is equal to the concentration of the corresponding reactant, the term for that species in the reaction quotient equation is 1.
For heterogeneous reactions involving solids or pure liquids:
Terms involving concentrations of solids or pure liquids are treated as constants and are equal to 1.
At equilibrium:
All terms in the reaction quotient equation (except for solids and pure liquids) are equal to their equilibrium concentrations or pressures, resulting in Q = K (the equilibrium constant).
During the reaction:
If the reaction is not at equilibrium, terms in the reaction quotient equation differ from 1, indicating that the reaction has not yet reached equilibrium.
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- Posts: 40
- Joined: Mon Jan 09, 2023 9:25 am
Re: Constants in Q Equation
A term in the equation for the reaction quotient Q will equal 1 when:
gases: The partial pressure of that gas is 1 atm
solids/liquids: The activity of that substance is 1
solutions (aqueous): The molar concentration of that species is 1 M
So any pure solids, pure liquids, or solutions at 1 M concentration will have their term in Q equal to 1. Gases will have their term = 1 if their partial pressure is 1 atm.
gases: The partial pressure of that gas is 1 atm
solids/liquids: The activity of that substance is 1
solutions (aqueous): The molar concentration of that species is 1 M
So any pure solids, pure liquids, or solutions at 1 M concentration will have their term in Q equal to 1. Gases will have their term = 1 if their partial pressure is 1 atm.
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