Reaction Coefficient, Q

[ryan_macdougall_3B_2C]

On page 431 of the textbook it introduces the formula for the reaction coefficient:
Q = [(a subC)^c x (a subD)^d]/ [(a subA)^a x (a subB)^b] . What does this equation tell us, when is it useful, and what do the variables stand for? The book did not explain this well.

[Thu Uyen Tran 1B]

Q, in comparison to K, tells us whether reaction is favors the products or reactants. When Q>K, the reaction favors reactants. When Q<K, the reaction favors the products. It's basically products/reactants, each component raised to the number of moles in the chemical formula.

[Max Mazo 2C]

The lowercase letters a, b, c, and d all refer to the molar coefficients of each part of the reaction, and the upper case letters A, B, C, and D refer to the components of the reaction, with C and D as products and A and B as reactants.