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Basic Chemical Equilibrium
- Chemical equilibrium is the location in a reaction that the concentrations of all reactants and products stay constant over a long period of time. Chemical equilibrium occurs in any reaction that is done in a closed system.
-Equilirium is not when a reaction has stopped or become complete. It is a balance between the foreward reaction and the backward reaction. An example of this is when sugar is dissolved in water. Although not a chemical reaction, the equilibriumidea still applies. The solid sugar is dissolving at the same rate as dissolved sugar is re-forming. This is basic equilibrium.
Equation
[C]c [D}d
K= _________
[A]a [b]b
Steps to solve an equilibrium equation.
1- Change the A,B,C,D in the equation to the chemicals in your reaction. Products go on top and reactants go on the bottem. The powers in the equation are the numhers in the chemical equation that tell you the molar ratios.
2- Plug in the given molarities for the chemicals.
3- Solve for K, which is your equilibrium constant.
Note- The equation can also be done when you are given a K and a molarity asked to find the concentrations of the other chemicals. The same process of pulgging in and solving for the unknown applies.< br>
Example
-Find K for the reaction H2O2-> H2O + O2
[H2O2]=1M [H2O]=1M [O2]= .5M
1- Plug into the equation and get > [H2O] [O2]
K= _________
[H2O2]
2- Then, change the chemical formulas to the given molarities. >
[1.00M] [0.50M]
K=______________
[1.00M]
3- Then, solve for the unknown. K= 0.5M
ExampleProblem