(a) (i) State three characteristic properties of transition metals.

(ii) What is the oxidation state of manganese In each of the following species? (1) MnCl\(_2\) (II) MnO\(_2\) (III) MnO\(_4^{-}\)

(iii) Explain why manganese conducts electricity in the solid state but manganese chloride conducts only when molten or in solution.

 

(b)(i) The collision theory suggests that for two particles to react, they must collide. What two factors determine whether or not the collision would lead to formation of products?

(ii) Use an energy profile diagram to illustrate what is meant by the enthalpy change (\(\Delta\)H) and the activation energy (E\(_A\)) of a reaction.

 

(c) When few drops of aqueous KSCN are added to a solution of iron (III) salt the following equilibrium is set up:

Fe\(^{3}_{(aq)}\) + 3SCN\(^{-}_{(aq)}\) \(\rightleftharpoons\) Fe(SCN)\(_{3(aq)}\) 

yellow       colourless               deep red

The equilibrium mixture has a pale red colour.

(i) Explain what would happen if more KSCN\(_{(aq)}\) were added to the equilibrium mixture.

(ii) Which of the ions in the equilibrium mixture forms an insoluble hydroxide with NaOH\(_{(aq)}\)? Write an equation for the reaction
(iii) State two changes observed on adding NaOH\(_{(aq)}\) to the equilibrium mixture.