[nonlinear]

I wanted to know if my thinking is correct: Keq depends only on temperature of the system because heat is often a product or reactant (depending on endo or exothermic), so you can think of that as.. something that will raise/lower the concentrations of other products and reactants that will be included in the Keq equation.

... Just wanted to make sure. Please correct me if I am mistaken! Thank you!

[Borek]

Please elaborate, I am not sure if I understand what you mean.

[nonlinear]

I'm not sure how else to put it. But why does Keq depend only on temperature and not the concentrations of products and solutions? I thought the equation for Keq was [products] / [reactants] , so wouldn't it make sense that it'd depend on the concentrations of products and reactants and not only the temperature?

[Borek]

No, that's the beauty of equilibrium - for a given reaction at equilibrium reaction quotient is always identical and equals Keq. When reaction quotient is not equal to Keq, you are not at equilibrium and system will react till it gets to Keq. How fast it will get there depends on the reaction kinetics, so sometimes it is almost impossible to observe system with Q <> Keq (for example neutralization reactions are very fast), sometimes reaction is slow and after mixing Q<>Keq.

[nonlinear]

Equilibrium can occur at any temperature, right? Or no? I'm a bit confused about the difference between Q and Keq.

[Borek]

Equilibrium can occur at any temperature, right?

Yes. Keq will have different value, so if you have a system at equilibrium and at given temperature, and you change the temperature, system has to respond somehow (reacting) to get to the equilibrium again.

Q can take any value - it just describes the system as it is. Keq (for a given temperature) has one value.

[nonlinear]

Q can be described in terms of partial pressures or concentration.. correct?