# equilibrium constant

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Thread starter 1 year ago
#1
why do we times the concentrations and raise the power to the concentration when calculating the equilibrium constant. I'm in year 12 and don't understand why this is the case as to find the ratio of concentration of products to reactants why don't you add the concentration of products and divide by concentration of reactants to get the equilibrium constant
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1 year ago
#2
it's got something to do with reaction kinetics
... which I wouldn't concern myself with it if I were you. just accept that that's the case
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1 year ago
#3
(Original post by utv)
why do we times the concentrations and raise the power to the concentration when calculating the equilibrium constant. I'm in year 12 and don't understand why this is the case as to find the ratio of concentration of products to reactants why don't you add the concentration of products and divide by concentration of reactants to get the equilibrium constant
Why do you divide distance by time to get speed? It is just what you do. Likewise, this is what we do with Kc calcs.

You need to turn it around and think about the experiments people did, back in the day. They mixed chemicals together and measured concs when equilibrium was achieved. They did this for various equilibria and then looked for patterns. The pattern they found, which always described their equilibria involved multiplying and powers. That's just what the equilibria do.
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Thread starter 1 year ago
#4
thanks for the reply. when the equilibrium constant equals 1 we say equilibrium is reached because the ratio is 1:1

this means we have the same concentration of reactants and products but I thought equilibrium ment constant concentration not same. may you explain any misunderstanding which I have ?
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1 year ago
#5
(Original post by utv)
thanks for the reply. when the equilibrium constant equals 1 we say equilibrium is reached because the ratio is 1:1

this means we have the same concentration of reactants and products but I thought equilibrium ment constant concentration not same. may you explain any misunderstanding which I have ?
It is more of a case of the opposite way around: at dynamic equilibrium, the concentrations do not change, i.e. they remain the same, but not necessarily the same as each other. They can be the same, but they don't have to be. Just so long as they remain constant.
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Thread starter 1 year ago
#6
so why is the equilibrium constant one? as doesn't this mean both concentrations are equal? even though like you said they are not the same as each other.

as an equilibrium constant if I'm correct is the ratio of concentration of products : concentration of reactants. so if this equals 1 then surley this means the concentration must be exactly the same.
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