E5 Le Chatelier's Principle 2. Complex ion equilibria (a) The Thiocyanatoiron(III) Complex Ion Write the equation for this equilibrium {Eq'n (5)}. The complex ion, [Fe(H2O)(SCN)]2+, is responsible for the observed red color. Compare the intensity of the red color upon addition of each of the following with the intensity of the color in tube 4. Interpret your observations in terms of the equation describing the equilibrium and Le Chtelier's principle. (1) Fe(NO3)3 - intensity of red color: lighter / darker {circle your choice equilibrium position shifts: left right {circle your choice} (ii) KSCN - intensity of red color: lighter / darker equilibrium position shifts: left right {circle your choice {circle your choice} (iii) NaOH {The brown precipitate formed is due to the reaction: Fe3+ + 3 OH = Fe(OH)3(s).} intensity of red color: lighter / darker / disappears {circle your choice} equilibrium position shifts: left right {circle your choice (b) The Temperature-Dependent Equilibrium of Co(II) Complex Ions Write the equation for this equilibrium Equation (6]. (i) What happens when you add 12 M HCl (or Cl*) to the pink (aquo) complex? solution turns: blue-purple/pink; equilibrium shifts: left right {circle your choices} (ii) What happens when you heat the pink (aquo) complex and when you cool it? solution heated: it turns blue-purple / pink; solution cooled: it turns blue-purple / pink {circle your choices} (iii) Explain why these results occur in terms of the equation describing the equilibrium and Le Chtelier's principle. 3. The equilibria of saturated solutions (a) Saturated Sodium Chloride (i) What happens when 12 M HCl is added to saturated (5.4 M) NaCl? nothing solution turn transparent a precipitate forms {circle your choice (ii) The concentration, [Cl], in the original saturated solution is 5.4 M. What is the [CH-] concentration just after addition of the 12 M HCl, and before anything occurs? -9