AS Equilibrium Constant question.

[boiboi95]

For reaction A > 2B

Kc: [B^2]/[A]

When you increase the pressure, more molecules of B are converted to A to attempt to decrease the pressure. (Net backward > net forward)

Doesn't it mean the concentration of B decrease and concentration of A increase, making the overall Kc decrease?

But I've learned that Kc doesn't change when pressure changes.

Does it mean initially, right after the pressure was increased, B molecules convert to A molecules to decrease the pressure, but the increased concentration of A, at the end, will convert back to the original concentration of B to reach the original Kc again?

Then if it is true, does it mean the overall pressure of the reaction is still increased? Despite the efforts of the molecules trying to decrease the pressure of the reaction?

I've read in a thread from the forum: Does a change in pressure change the equilibrium constant? but I'm still confused, a bit.

*Edit: By Kc, I meant the ratio/quotient of [B^2]/[A] in some parts above where I went wrong.

[lzxnl]

Ah, think carefully about what happens when the pressure changes. By the ideal gas law, if the pressure increases, the volume drops. Therefore, the concentration increases. If you increase the concentration, Q increases and the reaction therefore attempts to reduce Q back to Kc.
You have two things confused. What changes is the Q value, which is the fraction that you have stated. What does NOT change, Kc, is the Q values AT EQUILIBRIUM. This does NOT change unless you change the temperature.
Q=[B^2]/[A] at any time. Kc=Q only when the reaction is at equilibrium.
As for the overall pressure, Le Chatelier's principle states that the system cannot totally offset any changes to equilibrium, so the pressure will still have a net increase.