If the Equilibrium constant stands for the extent of reaction at equilibrium, whether more of forward or backward reaction is taking place, then why is it not affected by factors like concentration of reactants and product?

For example, if you increase concentration of reactant, equilibrium will shift to the right, which means more of forward reaction is taking place, so shouldn'tthe equilibrium constant change?

  • $\begingroup$ The right explanation lies on very complicated thermodynamic equations, sice I do not know the depth of the answer I'll just say that the $K_{\mathrm{eq.}}$ is only dependent od temperature, because whatever Reactants/Products concentration (activity) you'll have at $T$, the quotioent between those will always reach a fixed value. $\endgroup$
    – TheVal
    Commented Oct 20, 2013 at 10:25
  • 1
    $\begingroup$ Welcome to Chemistry Stack Exchange! This is an excellent question on a topic that confuses many. $K$ defines the allowable values of $Q$ that constitute equilibrium. $Q$ can change, but at fixed temperature, $K$ will not. Because it is so confusing to many, this question has already been asked and answered. See chemistry.stackexchange.com/questions/4977/… and read both answers, which approach the problem in different ways. $\endgroup$
    – Ben Norris
    Commented Oct 20, 2013 at 10:28


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