44. IRREVERSIBLE AND REVERSIBLE REACTIONS

Chemical reactions consist in interaction of reagents with formation of products reaktsiiya. It is not necessary to believe, however, that the direction of chemical reaction only one. Actually, chemical reactions proceed both in direct, and in the return the directions:

Reagents Products

All chemical reactions, in principle, are reversible.
It means that in reaction mixture both interaction of reagents, and interaction of products proceeds. In this sense distinction between reagents and products conditional. The direction of course of chemical reaction is defined by conditions of its carrying out (temperature, pressure, concentration of substances).
Many reactions have one preferential direction and for carrying out such reactions in opposite direction extreme conditions are required. In similar reactions there is almost full transformation of reagents into products.

Example. Iron and sulfur at moderate heating react among themselves with formation of iron sulfide (II), FeS is under such circumstances steady and practically does not decay on iron and sulfur:

Fe + S FeS

Example. Fusion reaction of ammonia is reversible:

N2 + 3H2 2NH3

 

At 200 atm and 400 0C the maximum and equal 36% (on volume) the maintenance of NH3 in reaction mixture are reached. At further temperature increase owing to the strengthened course of reverse reaction volume ratio of ammonia in mix decreases.
Direct and return reactions proceed at the same time in opposite directions.

In all reversible reactions the speed of direct reaction decreases, the speed of reverse reaction increases until both speeds do not become equal and balanced state will not be established.

In balanced state of speed of direct and reverse reaction become equal.

   

 

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