1. Read the problem,.... carefully

            isolate the chemical equation, write it, balance it.

            what is the actual question? (may be different language)

                        find Keq,    find direction of reaction (if..)                 find final composition

 

2. Identify a source for all but one variable

            find Keq (unless, of course, that’s the goal)          

                        you might find Keq value for the reverse reaction or for Kc (but not Kp)

            identify the initial conditions, if given

                        you may need to relate data to concentrations, etc.

 

3. Is this “find Keq” ?

            If so, find all other variables -- concentration, pressure

            substitute into Keq and compute K

 

4. Is this a “Q” problem .... Given these conditions, in what way will conc / pressures change?

            treat Keq as Q =

            substitute the original, nonequil values

            is Q >, = < Keq

 

5. Is this a “find the equilibrium concentrations/pressures” for a set of initial conditions

            identify the initial conditions (again, language may disguise some information)

                        need to recognize difference between label and actual equil conc.

            select a variable for change (the “x”)

                        link all other changes to x

                        write, algebraically, all final concentrations (using initial value, x)

            substitute in Keq expression

                        rewrite as one equation with x as the only unknown

                        solve

                                    ... may be easy, might be quadratic

                                    ... next chapter, might cheat and simplify

                                                (especially useful if Keq  is very large or small)

                                    ... if worse comes to worse, trial and error numerical approach

 

6. LeChatlier ... system at equilibrium now

            what if ... we changed some condition....

 

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Living in Boiling Acid ?

            3:30 today  (Friday) in Union Theater

            Life Under Extreme Conditions  (Yellowstone Hot Springs are Teeming with Life)

                                    Almost all DNA testing depends on that information