See the BOLD part below. Under certain conditions, the product of the reaction b
ID: 1022580 • Letter: S
Question
See the BOLD part below.
Under certain conditions, the product of the reaction between iron (III) ions and thiocyanate ions is the dithiocyanate iron (III) ion, Fe(SCN)2+.
Write an equation for the reaction in which dithiocyanate iron (III) ions are produced.
Fe3+ + 2SCN- <=> Fe(SCN)2+
Write the equilibrium-constant expression for the equation written in part A.
Kc = [Fe(SCN)2+]/[Fe3+] • [SCN-]2
Explain how your experimentally determined values of Kc would be affected if this reaction occurred to any significant extent in your experiment.
Explanation / Answer
Note that if you are doing this at constant Temperature, Pressure and humidity, then the value of Kc should NOT change.
That is why it is called a constant of equilibrium, since the ratio will reamain as long as you don't change T,P,H, etc...
If you were to react 100% or 80%; the Kc value will be always the same at such T,P conditions.
The only thing you could be doing wrong is experimental error. Those are carried along since you may be doing wrong lab practices.
Some practices that may change the value of Kc are:
- Incorrectly measuring/weighting the mass
- Incorrectly accounting for volume measurements
- Incorrect calculation
- Wrong stoichiometric ratios