Question

I don't understand what the reaction quotient is, anyone care to explain?

Answer 1

If we're talking about equilibria, the reaction quotient tells you which direction a reaction is likely to proceed when you compare it to that reaction's Keq. Keq is calculated as [P]/[R], the concentration of products at equilibrium divided by the concentration of reactants at equilibrium. If Keq is very large, it means the forward reaction (i.e. towards forming products) will be favoured, but if Keq is very small, it means the reverse reaction (i.e. towards forming reactants) will be favoured.

Q is calculated in the same way as Keq, except you're using the concentrations of reactants and products for your specific situation, which might not represent equilibrium concentrations. If Q is greater than Keq for that reaction, it means you have too many products and so the reverse reaction will be favoured. If Q is less than Keq, it means you have too many reactants and so the forward reaction will be favoured.

If you're given concentrations for both reactants and products in a question, always calculate Q so that when you construct your ICE table, you know which side is decreasing in concentration and which side is increasing. Side note: if any compound in the reaction starts at 0, the reaction can only proceed to that side and so Q will not need to be calculated.

If anything is unclear let me know - hope this helps!

Answer 2

So the reaction quotient is using the initial concentrations as opposed to the final equilibrium concentrations that Keq uses?

Answer 3

Exactly!

Answer 4

Coolios

Answer 5

Don't Forget, to Close Question Too !

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