CHEMICAL MONITORING

AND MANAGEMENT

Year 12 Chemistry

9.4.1Much of the work of chemists involves monitoring the reactants

and products of reactions and managing reaction conditions

THE ROLE OF THE CHEMIST

A variety of industries employ chemists. Some of these include:

Inorganic chemical synthesis Organic chemical synthesis Petrochemical industry Pharmaceutical industry Plastics industry Mining industry Food processing Environmental analysis

Chemists work with a variety of other professionals including plant managers, engineers, computer programmers and plant operators. It is essential that chemists are able to communicate with a variety of people from a different academic backgrounds

INORGANIC SYNTHESIS CHEMIST

Chemists in this role assist in the production of chemicals such as:

Ammonia Fertilisers Explosives Various acids

Source: www.careers-scotland.org.uk

These chemists are concerned with quality control of final products and may be involved in the development of new products.

ORGANIC SYNTHESIS CHEMIST

Chemists in this role assist in the production of chemicals such as:

solvents detergents dyes pesticides herbicides Source: www.raci.org.au

These chemists are concerned with quality control of final products and may be involved in the development of new products.

PETROCHEMICAL CHEMISTChemists in this role are involved in the

production of: Petrol Kerosene Natural gas LPG Oils

Source: www.kingsu.net

These chemists are concerned with maximum yield, quality control of final products and may be involved in the development of new products.

MINING INDUSTRY

Chemists in this role do a variety of tasks including:

Environmental reclamation Purification of minerals Extraction of metals Research Analytical testing

Source: www.ela-iet.com

ENVIRONMENTAL CHEMISTChemists in these roles perform a variety

of duties to monitor and protect the natural environment. Some roles include:

Monitoring water supplies Monitoring air quality Monitoring soil contamination Analysing effluent from industry

Source: www.careercornerstone.orgChemists in this role use a variety of analytical techniques including wet chemical and modern instrumental analysis to monitor chemical contamination in the environment

COMBUSTION NEEDS MONITORING

The products from the combustion of petrol depend upon the conditions of the reaction

Complete combustion (plenty of O2)

2C8H18 (l) + 25O2 (g) 16CO2 (g) + 18H2O (l)

Incomplete combustion (insufficient O2)

C8H18 (l) + O2 (g) CO2 (g) + CO (g) + C (s) + H2O (l) + unburnt hydrocarbons

(not balanced)

Note the additional products in the incomplete combustion. Extra CO is poisonous, C represents soot and unburnt hydrocarbons from exhaust pollute our cities. Poorly tuned vehicles and inefficient mufflers (loud ones!) result in these problems

Source: www.treehugger.com

9.4.2Chemical processes in industry require

monitoring and management to maximise production

PRODUCTION OF AMMONIA – THE HABER PROCESSIn 1912, German scientist, Fritz Haber

developed a process for manufacturing ammonia from nitrogen and hydrogen.

N2 (g) + 3H2 (g) 2NH3 (g) + 92kJ

Source: www.bbc.co.uk

Notice that this reaction is reversible which can establish equilibrium. This means that Le Chatelier’s Principle applies to the chemistry of this process.Also, note that the forward reaction is exothermic

SCHEMATIC OF THE HABER PROCESS

Source: Chemistry Contexts 2, 2006

Notice the lack of waste in this process. All unreacted gases are recycled and heat can be collected to be used in the reaction vessel

Ammonia is made here

INDUSTRIAL USES OF AMMONIA

Fertilisers for plants – plants need nitrogen in the form of ammonium and nitrate salts. These are manufactured from ammonia.

Metal extraction – examples are Ni and Au

Cleaning agents Production a cyanide for plastics

manufacturing Manufacture of synthetic materials

such as nylon Manufacture of explosives Manufacture of some

pharmaceuticals

AMMONIA AND LE CHATELIER

N2 (g) + 3H2 (g) 2NH3 (g) + 92kJ

Using your knowledge of Le Chatelier’s Principle, describe what the optimum conditions (in terms of yield and rate) for this reaction will be in relation to the following:

Temperature Pressure Use of a catalyst

OPTIMUM AMMONIA PRODUCTION

Rate

Yield

Cost

Source: Chemistry Contexts 2, 2006

9.4.3Manufactured products, including food, drugs and household

chemicals, are analysed to determine or ensure their chemical composition

ATOMIC ABSORPTION SPECTROSCOPY (AAS)Invented by an Australian, this technology is used to detect

low concentrations (ppm, ppb) of metal ions in solutions. This is useful in Agriculture and Environmental monitoring.

Australian, Alan Walsh invented the first working AAS in 1952

WET CHEMICAL TESTS FOR IONSAnions Cl-, SO4

2-, CO32-,

PO43-

Ppt testsAg+ forms insol

compounds with chloride, carbonate and phosphate

Ba2+ forms insol compound with sulfate

Cations Ba2+, Ca2+, Cu2+,

Pb2+, Fe2+, Fe3+

Flame testsSee p 218 in text

Ppt testsHCl forms insol cpd

with leadNH3 forms insol cpd

with many others (see flow chart)

See exp’t 35 – “Hunt for Ions”