Q and K

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Alison Trinh 1E
Posts: 104
Joined: Thu Jul 25, 2019 12:16 am

Q and K

Postby Alison Trinh 1E » Sun Feb 09, 2020 11:43 pm

Why do we need to compare the values of Q and K?

Nicholas Chin 1G
Posts: 100
Joined: Thu Jul 11, 2019 12:17 am

Re: Q and K

Postby Nicholas Chin 1G » Sun Feb 09, 2020 11:44 pm

K is a constant for a reaction that tells you the concentrations of products and reactants needed for the reaction to be at equilibrium. Q is not a constant, and can be calculated (and is different) at any point in a reaction. The value of Q compared to K tells you which way the reaction is going at that moment.

Alondra
Posts: 36
Joined: Tue Feb 26, 2019 12:15 am

Re: Q and K

Postby Alondra » Sun Feb 09, 2020 11:50 pm

K is a ratio that represents the system at equilibrium while Q is at any given state. you compare them to know whether the forwards (products) or reverse (reactants) rxn will be favored.

805394719
Posts: 104
Joined: Wed Sep 11, 2019 12:16 am

Re: Q and K

Postby 805394719 » Sun Feb 09, 2020 11:51 pm

K is the constant that gives the ratio of equilibrium concentrations of a reaction whereas Q gives the ratio of the concentration of the products to the reactants at any given point in time as the reaction is occurring. They are both calculated the same way, however, Q can be calculated at any point in time whereas K is only calculated when the reaction has reached equilibrium. Calculating Q provides a way of knowing which way the reaction will proceed. For example, if Q < K, then the reaction has not reached equilibrium and the equilibrium ratios have not yet been attained and the reaction will proceed in the forward reaction. If Q > K, then the reaction will proceed in the reverse reaction since the equilibrium constant is smaller than the current ratios.


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