K vs Q [ENDORSED]

[Karyn Nguyen 1K]

What's the difference between the formula for the equilibrium constant K and the formula for the reaction quotient Q?

[ariana_apopei1K]

Q changes as a reaction occurs, and K is when said reaction reaches equilibrium. If the reaction does't reach equilibrium, you can't use K, only Q

[Chloe Likwong 2K]

The formula is the same. What's different between the two is the concept behind it. The equilibrium constant K is the ratio at equilibrium; it describes a reaction that is at equilibrium. On the other hand, the reaction quotient pertains to the ratio at any given time of the reaction.

This might elucidate the topic further: viewtopic.php?f=50&t=24065

[Matthew Tran 1H]

The formula for K and Q is the same; the difference is that the numbers you plug in for K must be the equilibrium partial pressures or concentrations while for Q you can plug in the partial pressures or concentrations at any point in the reaction, not just at equilibrium.

[Aleeque Marselian 1A]

The formula to find K and Q are the same. However, K is the ratio of at equilibrium and therefore includes the values of the reaction at equilibrium. Meanwhile, Q is the reaction quotient and is the ratio at any given time in the reaction.

[vaishali 1D]

The formula is the same, but K is the ratio at equilibrium, whereas Q is the reaction quotient. The numbers you plug in decide whether you're using K or Q.

[Jchellis 1I]

So can there be only one value for K but multiple values for Q as the reaction progresses?

[allisoncarr1i]

The partial pressures and concentrations do not have to be at equilibrium for Q but they do for K. Other than that, it's the same equation.