# PARAMETERS FOR SPECIFYING INDUSTRIAL CHEMICAL REACTIONS

Chemical reactions are inevitable phenomenon,
it can either be occurring physically or in the present of great deal of thermal
energy. Chemical industries are able to perform certain industrial operations
through series of chemical reactions and conversions.

Some chemical reaction are
endothermic, exothermic, volatile, some are achievable. Most important
mathematical parameters for specifying and characterizing chemical reactions in
the process industry include the following

1.  Yield
2.    Conversion
3.  Selectivity
4.  Space-time
yield
These
parameters are generally expressed in mole -% or weight-% (weight percentage)
or volume percentage (Volume-%)
YIELD ; This refers to the portion or fraction
of feed stocks that is raw materials recovered as the main or major or desired
product and is  the quotient of the
amount of desired reaction QR and the amount of a starting component QF
YIELD
(%) =    QR/QF X100
Where
QR   = This is the amount of reaction
desired product formed
QF
=  The starting component of the
raw materials or feed stocks
CONVERSION
This
term may be laterally used in illustrating the quantity of reactant converted
during a single run through an apparatus involving multiple runs in a systemic
process.
One
of the greatest challenges often encountered by the production engineer and
chemist is to explore the possibility of equating the percentage conversion
with the percentage yield in a single pass to reduce the cost of production. To
achieve this odious task, careful manipulation of the data or variable involved
in the production process such as changing operations condition, raising the
pressure or temperature, and use of catalyst is seemingly employed.
SELECTIVITY
The
selectivity of a reaction product makes an important statement concerning
competitive reactions, which can result in the feedstock forming reaction
products other than desired product. The selectivity of a reaction product is
the quotient of the amount of reaction product QR and the amount of converted
feed stock component QC,
Mathematically
Selectivity in % =     QR

QC                              X
100
Where
QR = Amount of reaction product
QC      = Amount of converted feedstock
It
is imperative to understand and note that the yield is always less than the
selectivity if the conversion of the reaction partner is less than 100% . The
values for yield and selectivity are only identical if there is 100%
conversion. Conversion, selectivity and yield are connected mathematically by
the relationship below
YIELD =                         Conversion X
Selectivity

100
That
is yield is equal conversion times selectivity over 100
SPACE – TIME – YIELD
The
frequently used quantity in the industry gives the amount of reaction product
formed per unit volume of catalyst per unit time and is termed catalyst
efficiency.