## Q versus K

Gabriella Bates 2L
Posts: 95
Joined: Thu Jul 11, 2019 12:15 am

### Q versus K

Can someone explain the different between K and Q? How can Q be used to tell us the direction the reaction will proceed? Thanks in advance!

Phuong Tran 1G
Posts: 33
Joined: Sat Sep 14, 2019 12:16 am

### Re: Q versus K

Q is the reaction quotient and has the same formula as K. Q would be equal to the concentrations of the product over the concentrations of the reactants. However, unlike K, Q can be used even when the equation isn’t in equilibrium. You then use Q and compare it to K to see how far the reaction is from equilibrium.

If Q>K, there is more product than at equilibrium (or not enough reactant) and so the reaction would proceed in the reverse direction

If Q=K, the equation is already at equilibrium

If Q<K, there is less product than at equilibrium and so the reaction would proceed forward.

Andrew Liang 1I
Posts: 94
Joined: Fri Aug 30, 2019 12:18 am

### Re: Q versus K

We calculate Q and K the same way (product/reactant). However we use Q when we are unsure whether the chemical reaction is at equilibrium yet. If Q is greater than K then it means that there is still more product that need to be reacted; therefore, it is a reverse reaction going from product to reactants. On the other hand, if Q is smaller than K then it means that there is still more reactants that need to be reacted; therefore it is a forward reaction going from reactants to product. Last scenario, if Q is equal to K then it means that the reaction has reached equilibrium.

Caroline Beecher 2H
Posts: 34
Joined: Wed Nov 14, 2018 12:21 am

### Re: Q versus K

An example of using Q in comparison to K we did as an example in class with the reaction: N2O4(g) == 2NO2(g). Partial pressures of the two gases were given, and the goal was to see if the system was at equilibrium at this specific point in the reaction. The Qp ended up being less than the Kp, meaning at that specific time the reaction was not in equilibrium and would therefore proceed toward the products (to the right).