Changing the way you learn

Question	Answer
Reaction rate	The speed of a chemical reaction may be defined as the change in concentration of a substance divided by the time interval during which this change is observed
Image: Velocidad De Rx (binary/octet-stream)	For a reaction of the form A+B→C , the rate can be expressed in terms of the change in concentration of any of its components
Image: Velocidad Expresion (binary/octet-stream)	Image: Rate Of Reaction3 (binary/octet-stream)
in which Δ[A] is the difference between the concentration of A over the time interval t2 – t1:	Image: Cambio De Concentración (binary/octet-stream)
Notice the minus signs in the first two examples above. The concentration of a reactant always decreases with time, so Δ[A] and Δ[A] are both negative.	Since negative rates do not make much sense, rates expressed in terms of a reactant concentration are always preceded by a minus sign to make the rate come out positive.
Consider now a reaction in which the coefficients are different: Image: Ecuación (binary/octet-stream)	t is clear that [B] decreases three times as rapidly as [A] , so in order to avoid ambiguity when expressing the rate in terms of different components, it is customary to divide each change in concentration by the appropriate coefficient:
Image: Expresión De Velocidad (binary/octet-stream)	Image: Cambio De Concetración (binary/octet-stream)

reaction rate

	Created by Alvaro Vargas Calero about 6 years ago