Q.(a)
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Start your 14-day free trial to unlock the full solution →(a) Cell notation is a standard shorthand placing the anode on the left and cathode on the right of a double vertical line (salt bridge); gold number measures a protective colloid's effectiveness. (b) The Lucas test distinguishes 1°, 2°, 3° alcohols by how fast each reacts (turbidity) with Lucas reagent.
(a)(i) Galvanic cell notation: By convention, a galvanic (voltaic) cell is represented with the anode (where oxidation occurs, the negative electrode) written on the left, and the cathode (where reduction occurs, the positive electrode) written on the right. A single vertical line, '|', denotes a phase boundary (e.g. between a solid electrode and its electrolyte solution); a double vertical line, '||', denotes the salt bridge separating the two half-cells. Concentrations of the electrolyte solutions are usually indicated in parentheses. For example, the Daniell cell (Zn electrode in solution, connected via a salt bridge to a Cu electrode in solution) is written: where zinc (anode) is oxidised, , and copper (cathode) is reduced, .
(a)(ii) Gold number: Gold number is defined as the minimum mass, in milligrams, of a protective colloid (such as gelatin, starch, or gum arabic) that must be added to 10 mL of a standard red gold sol to just prevent it from coagulating (changing colour from red to blue/violet) when 1 mL of a 10% sodium chloride solution is subsequently added. A smaller gold number indicates a more effective protective colloid (less of it is needed to protect the gold sol from the coagulating electrolyte).
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