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Q

Posted: Sun Jan 12, 2020 10:01 pm
What is the purpose of finding Q? Is it just to determine the direction of the reaction?

Re: Q

Posted: Sun Jan 12, 2020 10:05 pm
Yes, this is basically the only use.

Re: Q

Posted: Sun Jan 12, 2020 10:08 pm
Its useful to predict the direction of a reaction since you can find Q even if the system is not at equilibrium. If K is known, and you can measure Q, then you determine which side a reaction will favor until it reaches equilibrium. If Q<K, then the reaction will favor products until K is reached. If Q>K, then the reaction will favor reactants until K is reached.

Re: Q

Posted: Sun Jan 12, 2020 10:10 pm
Q, or the "reaction quotient", measures the relative amount of reactants and products at a certain time. It essentially describes a reaction when it's not in equilibrium and what direction will be taken for it for equilibrium to be restored (hence the favoring of a forward or reverse reaction)

Re: Q

Posted: Sun Jan 12, 2020 10:26 pm
If we are at the reaction equilibrium but we aren't sure would we use Q?

Re: Q

Posted: Sun Jan 12, 2020 10:27 pm
Q helps to determine or predict the path a reaction will take after a specific time. It can be compared to K to make assumptions about the reaction at hand.

Re: Q

Posted: Sun Jan 12, 2020 10:29 pm
You could calculate Q and if it matches K, then the reaction is at equilibrium.

Re: Q

Posted: Mon Jan 13, 2020 8:33 am
To add on, since Q is the relative ratio of products to reactants at a given instant, you know the reaction shifts right if Q<K and shifts left if Q>K.When Q=K, the reaction is at equilibrium. To summarize, finding Q helps you determine what direction the reaction will proceed based on the ratio between products to reactants

Re: Q

Posted: Mon Jan 13, 2020 8:38 am
Q expresses the relative ratio of products to reactants at a given instant not necessarily at equilibrium. This is mainly useful to compare to K in order to determine the direction of the reaction. When Q=K, the system is at equilibrium.

Re: Q

Posted: Mon Jan 13, 2020 10:28 pm
Q is the reaction quotient and tells us where the reaction is at currently relative to equilibrium. Note that for Q you do not need to use concentrations or partial pressures at equilibrium. However, for K we do. If Q<K product formation is favored and if Q>K reactant formation is favored. When Q=K the reaction is at equilibrium.

Re: Q

Posted: Mon Jan 13, 2020 11:39 pm
Q is the composition of a system at any time (even those other than equilibrium). It is an important indicator that tells you whether equilibrium lies in favor of products or reactants. when Q < K, the reaction will move toward the products, and if Q > K, the reaction will move towards the reactants, and if Q= K, the reaction is at equilibrium.