What is Q in equilibrium

The detailed explanation is as follows.

The expression for the reaction quotient, Q, looks like that used to calculate an equilibrium constant but Q can be calculated for any set of conditions, not just for equilibrium.

Q can be used to determine which direction a reaction will shift to reach equilibrium. If K > Q, a reaction will proceed forward, converting reactants into products. If K < Q, the reaction will proceed in the reverse direction, converting products into reactants. If Q = K then the system is already at equilibrium.

In order to determine Q we need to know:

• the equation for the reaction, including the physical states,
• the quantities of each species (molarities and/or pressures), all measured at the same moment in time.

To calculate Q:

• Write the expression for the reaction quotient.
• Find the molar concentrations or partial pressures of each species involved.
• Subsitute values into the expression and solve.

Hope it answers your question.
All the best!