|The Equilibrium Law|
|For any general reaction system the value of Keq
the equilibrium constant for the reaction. for example:
3 H2(g) + N2(g) <=====> 2 NH3(g)
Keq = [NH3]2
|The above equation is called the Equilibrium Law
it is a general form of the Law of Mass Action.
|Law of Mass Action|
|In a system at equilibrium, at a fixed temperature, the
of the equilibrium concentration of the products divided by the product
of the concentrations of the reactants, each being raised to the
of the substance in the equation, must be equal to a constant.
|This law can only be applied to ideal gases and solution.
are some reactions that do go all the way).
|Here is another example of an equilibrium law expression.
|H2(g) + I2(g)
<=====> 2 HI(g)
|Write equilibrium law expressions for each of the
|a) 2 NO(g) + O2(g) <=====> 2
b) 2 SO2(g) + O2(g) <======> 2 SO3(g)
c) SO2(g) + ½O2(g) <======> SO3(g)
d) SO3(g) <======> SO2(g) + ½O2(g)
e) 4 HCl(g) + O2(g) <======> 2
+ 2 Cl2(g)
|Some of the equations above are almost carbon copies of each other except for the values of the coefficients. A couple of general rules should help.|
|Any reaction written normally can have a Keq value.
does this Keq value stay the same if the reaction is
over and written in reverse. No, if the equation flips the Keq value
becomes the inverse.
At any given temperature there will be numerous [ ] values that will satisfy a constant Keq value.