Chemical Monitoring and Management

1. Much of the work of chemists involves monitoring the reactants and
products of reactions and managing reaction conditions

. Outline the role of a chemist employed in a named industry or
enterprise, identifying the branch of chemistry undertaken by the
chemist and explaining a chemical principle that the chemist uses


Gather, process and present information from secondary sources about the
work of practising scientists identifying:
- the variety of chemical occupations
- a specific chemical occupation for a more detailed study

The variety of chemical occupations

Environmental Chemists: Analyse and assess environment (air, water, soil)
data. This data is used to provide advice and information to authorities
(e.g. EPA) concerning air quality, water quality, soil quality, and
pollution levels.
They have detailed knowledge in:
- chemical analysis
- analytical procedures
- chemical concepts (e.g. how excess nitrate and phosphate can lead to
eutrophication)
- separation techniques (e.g. distillation)

Organic chemists: Studies the structure, properties, composition, and
reactions of carbon compounds.

Inorganic chemists: Studies the structure, properties, composition, and
reactions of all chemical compounds excluding organic compounds.

Analytical chemists: Examines and identifies the chemical make up of
substances in terms of structure, composition, and nature. They also study
the relations and interactions of different compounds through analytical
techniques. Find large use in the pharmaceutical industry, as well as in
the monitoring of air, water, and soil.

A specific chemical occupation for a more detailed study

(Analytical) Plant Chemist in the production of polyethylene: Examines and
identifies the chemical make up substances (alkanes, ethylene, waste water)
in terms of structure, composition, and nature in order to identify
impurities and monitor quality. (Burhan Gemikonakli)

Roles:
- Monitoring the quality of ethylene product from the cracking of longer
chain alkanes. Ensures quota quality is met by determining quantity of
impurities.
- Monitoring waste water before discharge to ensure it meets
environmental requirements (e.g. determining pH, concentration of
suspended solids, concentration of ions, etc.).
- Collaborating with engineers to adjust operating conditions to
optimise yield (e.g. increase temperature of cracking furnace)

Explaining a chemical principle that the chemist uses
- Adsorption (for gas-solid chromatography): The accumulation of liquid
on a solid forming a film of molecules.
- The separation is based on the different extents to which the
substances of the mixture (gaseous mobile phase) sticks onto the
surface (adsorption) of the stationary solid phase. The differing
degrees of adsorption affect the rate at which each substance passes
out the separating column, hence affecting separation.


- Solubility (for gas-liquid chromatography): Extent to which a solute
is able to be dissolved in a solvent
- The separation is based on the different extents in which the
substances of the mixture (gaseous mobile phase) dissolves into the
stationary liquid phase. The differing solubilities affect the rate at
which the substance passes through the separating column, hence
affecting separation.

. Identify the need for collaboration between chemists as they collect
and analyse data

- Different chemists specialise in different fields (e.g. procedures,
chemical concepts) and hence some problems are better solved with the
assistance of specialist chemists
- Reducing the workload, and thus increasing efficiency
- Communication of ideas to share knowledge for the advancement of
research
- Ensuring the reliability (repetitions of similar experiments) and
validity (ensuring data measured is accurate and relevant to desired
aim)


. Describe an example of a chemical reaction such as combustion, where
reactants form different products under different conditions and thus
would need monitoring

Chemists must monitor combustion reactions to ensure emissions released
into the environment are at an acceptable level.

Combustion with a sufficient oxygen supply
- Complete combustion occurs with the formation of carbon dioxide and
water
e.g. 2C8H18 (l) + 25O2 (g) > 16CO2 (g) + 18H2O (l)


Combustion with an insufficient oxygen supply
- Incomplete combustion occurs. Products released are usually either CO2
(g), C (s), CO (g), and water
e.g. 2C8H18 (l) + 17O2 (g) > 16CO (g) + 18H2O (l)
e.g. 2C8H18 (l) + 13O2 (g) > 8CO (g) + 8C (s) + 18H2O (l)

At sufficiently high temperatures, nitrogen gas in the air can react with
O2 (g) to form nitrous oxides (NO, NO2)
e.g. N2 (g) + O2 (g) > 2NO (g)
e.g. 2NO + O2 (g) > 2NO2 (g)

Also, sulfur impurities in fossil fuels such as coal and petrol can result
in the formation of SO2
e.g. S (s) + O2 (g) > 2SO2 (g)

Waste productions