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### Reaction quotient

Posted: Thu Jan 09, 2020 5:56 pm
I'm sure this has been asked before, but could someone explain how K and Q have different values even though the same principle is used to calculate both?

### Re: Reaction quotient

Posted: Thu Jan 09, 2020 6:00 pm
K and Q can have different values because the concentrations used the calculate them are different even though the method to do so is the same. Because Q can be calculated at any point during the reaction, the concentrations won't be constant like they would if you were calculating K.

### Re: Reaction quotient

Posted: Thu Jan 09, 2020 6:09 pm
Q, the reaction quotient, is calculated at any time during the reaction when the concentrations are different than at equilibrium and is usually compared to K, the equilibrium constant, to determine which direction a reaction will proceed. In this case, K will already be known so if the calculated value does not match the K value, it will be considered Q. If Q is less than K at some point during the reaction, then there are more reactants than products and the forward reaction is favored. If Q is greater than K at some point during the reaction, then there are more products than reactants and the reverse reaction is favored.

### Re: Reaction quotient

Posted: Sat Jan 11, 2020 3:29 pm
^^^ to go off what they said, if Q=K then the reaction is at equilibrium, so the concentrations would be the same as well

### Re: Reaction quotient

Posted: Sat Jan 11, 2020 3:41 pm
They have different values because K is only at equilibrium and Q can be calculated at any time during the reaction.

### Re: Reaction quotient

Posted: Sat Jan 11, 2020 3:46 pm
K is calculated at equilibrium , while Q is calculated anytime during the reaction

### Re: Reaction quotient

Posted: Sat Jan 11, 2020 4:04 pm
The reaction quotient is used to calculate the ratio of the reactant and product concentrations at any point as the reaction takes place. When the reaction quotient equals the equilibrium constant k, the reaction reaches equilibrium. Thus, the reaction quotient is used to calculate whether the forward or reverse reaction proceeds by looking at the concentrations of the products and reactants and comparing it to the k value. If the reaction quotient is smaller than k, the forward reaction is favored because there are more reactants than products, and if the reaction quotient is greater than k, the reverse reaction is favored since there are more products than reactants.

### Re: Reaction quotient

Posted: Sat Jan 11, 2020 4:14 pm
Q is the reaction quotient, which can be used anytime during a reaction dealing with gases. K is the equilibrium constant, so it can only be calculated once the reaction is at equilibrium.

### Re: Reaction quotient

Posted: Sun Jan 12, 2020 4:57 pm
K can only be calculated when the reaction has reached equilibrium. Q can be calculated at any point in a reaction.