Question

No chemical reaction takes place when granules of a solid, A, are mixed with the powder of another solid, B. However, when the mixture is heated, a reaction takes place between its components. One of the products, C, is a metal and settles down in the molten state while the other product, D, floats over it. It was observed that the reaction was highly exothermic.
(a) Based on the given information, make an assumption about A and B and write a chemical equation for the chemical reaction indicating the conditions of reaction, physical state of reactants and products and thermal status of the reaction.
(b) Mention any two types of reactions under which above chemical reaction can be classified.

Answer 1

(a) Solid A is assumed to be aluminium (Al) and solid B to be manganese oxide. When the mixture of manganese oxide and aluminium is heated, manganese is produced in the molten state and aluminium oxide floats over it. Manganese produced in the molten state as a lot of heat energy is released in the process. Therefore, C is manganese and D is aluminium oxide.
$\mathrm{Al}\left(\mathrm{s}\right)+{\mathrm{MnO}}_2\left(\mathrm{s}\right)\to \mathrm{Mn}\left(\mathrm{s}\right)+{\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)$

(b) The type of reaction under which the above reaction is classified are:
1. Redox reaction
2. Displacement reaction