The Reaction Quotient calculator computes the reaction quotient based on the concentration of two substances and two exponential coefficients.
INSTRUCTIONS: Choose units and enter the following:
Reaction Quotient (Q): The calculator returns the quotient as a real number.
The Reaction Quotient [1] formula, Q = [P]y / [R]x, is used to calculate the reaction quotient when a reaction is at any state other than equilibrium. Calculating reaction quotients can help determine the composition of a system as well as determine which way the reaction will proceed. A typical equation, xR = yP, can be used to represent a chemical reaction formula because [products] are always in the numerator, with [reactants] in the denominator. Therefore, the product "P" belongs in the numerator with reactant "R" in the denominator. Each variable is raised to its respective equation coefficient, y and x. The input variables are coefficients x and y (unit-less) and the concentrations of [P] and [R] in mols/L.
The formula for the Reaction Quotient is:
where:
Setting Q against K can provide useful information about which direction a reaction will proceed. It gives five possibilities:
Example:
aA + bB = dD + eE
Q= [products] / [reactants]
Q = [E]e [D]d / [B]b [A]a
References
[1] For the Spanish site click here
Whitten, et al. 10th Edition. Pp. 674