
Sketch a graph of resistance versus temperature for a conductor and a superconductor.

Important Questions on Materials


Kevlar can be made by reacting diaminobenzene, , with benzenedicarbonyl chloride, . Write the equation for the reaction of molecules of diaminobenzene reacting with molecules of benzenedicarbonyl chloride.

Hydroxyl free-radicals can be generated naturally in the body. This process is catalysed by iron in the following two steps:
Reaction 1: .
Reaction 2: .
Use the above information to write the uncatalysed reaction.

Hydroxyl free-radicals can be generated naturally in the body. This process is catalysed by iron in the following two steps:
Reaction 1: .
Reaction 2: .
Deduce whether iron is acting as a heterogeneous or homogeneous catalyst and justify your answer.

Hydroxyl free-radicals can be generated naturally in the body. This process is catalysed by iron in the following two steps:
Reaction 1: .
Reaction 2: .
Show that reactions 1 and 2 are redox equations by writing the oxidation half-equation and the reduction half-equation for each.

Heavy metals are often removed from solutions by precipitation. Use the Data booklet to calculate the concentration of sulphuric acid necessary to precipitate mercury() ions at a concentration of ? [].

Heavy metals are often removed from solutions by precipitation. Evaluate the effectiveness of this method for mercury removal and suggest improvements.
