Differentiate the following<br>(a) Redox reaction - disproportionation reaction<br>(b) Primary standard substance - Secondary standard substance<br>(c) Electrolysis - Hydrolysis<br>(d) Gangue - Slag<br>(e) Lattice energy - Hydration energy<br>(f) Equilibrium constant - Rate constant<br>(g) Ionic product - Solubility product<br>(h) Activation energy - Threshold energy<br>(i) Valence - Oxidation number<br>(j) Allotropy - Enantiotropy

PLACEHOLDER ANSWER - the answer is ten comparisons. (a) In a redox reaction one substance is oxidised and another reduced; in disproportionation the same element is both oxidised and reduced. (b) A primary standard is pure, stable and weighed directly to make a solution of exact concentration; a secondary standard's concentration must be found by titration against a primary standard. (c) Electrolysis is decomposition by an electric current; hydrolysis is reaction with water. (d) Gangue is the earthy impurity in an ore; slag is the fusible compound formed when flux combines with gangue. (e) Lattice energy is released when gaseous ions form a crystal; hydration energy is released when gaseous ions are surrounded by water. (f) The equilibrium constant is the ratio of concentrations at equilibrium; the rate constant is the proportionality constant in a rate law. (g) The ionic product is the product of ion concentrations at any moment; the solubility product is its value in a saturated solution at equilibrium. (h) Threshold energy is the minimum total energy colliding molecules need to react; activation energy is the extra energy over their average energy needed to reach it. (i) Valence is the combining capacity, a whole number without sign; oxidation number is the apparent charge on an atom and can be positive, negative, zero or fractional. (j) Allotropy is the existence of an element in different forms; enantiotropy is allotropy in which the two forms change into each other reversibly at a definite transition temperature (as with rhombic and monoclinic sulphur).