9.4 Chemical Monitoring and Management

Question 1

Identify an Australian Chemist, their industry, type of chemistry and chemical principles they use

Answer 1

Dr Oliver Hutt: CSIRO
Organic Chemistry: study of the compounds of carbon, synthesis of plastics and synthetic fibres, medicinal drugs, insecticides, fungicides and dyes.
Principles: collaboration with other chemists, analysis of raw material, monitoring waste products and new compounds are formed by rearranging atoms.

Question 2

Identify the need for collaboration between chemists and provide an example of where this occurs

Answer 2

• Increases knowledge and expertise
• highlights problems
• disseminate the results of investigations
  Eg: in the study of breast cancer, a biologist, nurse, doctor, synthetic chemist and physicist are required to work together

Question 3

Describe an example of how reactions which occur under different conditions produce different products.
Explain why these reactions need monitoring

Answer 3

Complete combustion occurs when there is an excess supply of oxygen: Hydrocarbon + oxygen -> Carbon dioxide and water
Incomplete combustion occurs when there is a limited supply of oxygen: Hydrocarbon + Oxygen -> Carbon dioxide + CO or C
These reactions need to be monitored in order to ensure maximum energy output, decrease the production of C (shot) which is pollutant and respiratory irritant, decrease the production of CO which is poisonous.

Question 4

Identify and describe 3 different types of chemists

Answer 4

Polymer Chemist - study and development of polymers
Food Chemist - investigation of the chemical aspects of food
Pharmaceutical Chemist - develops chemicals for use in medicine.

Question 5

Describe the chemical principles a Pharmaceutical chemist uses

Answer 5

• New compounds are formed by rearranging atoms
• stoichiometric calculations
• Collaboration with other chemists
• Analysis of raw materials to determine purity.

Question 6

Identify the industrial uses of ammonia

Answer 6

• Fertilisers
• Nitric acid: for explosives, fibres and plastics
• detergents (non-ionic surfactants)

Question 7

Recount the chemical reaction for the Haber Process

Answer 7

3H2 + N2 2NH3

Question 8

Is the Haber process exothermic or endothermic? Why?

Answer 8

Exothermic, as new bonds are formed, releasing energy.

Question 9

Define: rate of reaction

Answer 9

how long the reaction takes to reach equilibrium

Question 10

Explain why the rate of reaction is increased at higher temperatures, using the Haber process as an example

Answer 10

An increase in temperature increases the kinetic energy of molecules, which increased the rate of force of collisions between molecules. As a result of the reaction occurs faster.
This increases the yield of ammonia in the Haber process as the rate of reaction is increased. Yet, at too high a temperature, the yield of ammonia decreases.

Question 11

Explain why high temperatures decrease the yield of ammonia in the Haber process.

Answer 11

The Haber process is exothermic. Thus, according to Le Chatelier’s principle, the system will attempt to minimise the disturbance by moving equilibrium to the left in order to absorb excess heat. This reduces the yield of ammonia and increases the production of the reactants.

Question 12

Explain the ‘balancing act’ in the Haber process in relation to temperature, pressure and reaction rate.

Answer 12

Temperature: 400C. At high temperatures, which the reaction rate in increased, the yield decreases as the reaction is exothermic, At too low of a temperature, the reaction rate is decreased as there is not enough kinetic energy.
Pressure: 250 times atmospheric pressure. As high pressure, the yield of ammonia is increased. Yet due to safety considerations, the temperature is lower. This is because reactions at higher pressures are easily combustible and more expensive.

Question 13

Identify the catalyst used in the Haber process and explain its role

Answer 13

Magnetite (Fe3O4)
Used to increase the reaction rate by lowering the activation energy. This is because the catalyst is able to allow bonds in reactants to be broken faster, thus allowing the production of ammonia to occur faster.

Question 14

Explain the safety hazards of esterification

Answer 14

1. Use of alkanols and alkanoic acids. Highly volatile to are easily combustible gases. Reduced using a condensation tube.
2. Catalyst (sulphuric acid) is highly corrosive. Reduced by heating PPE.

Question 15

Explain why monitoring of the Haber process is required

Answer 15

Monitored in order to ensure maximum production of ammonia and safety.

1. Temperature and pressure: keep in range for optimum yield and safety.
2. Ratio of hydrogen and nitrogen gas: monitor to ensure no build up of reactants which would change the equilibrium.

Question 16

Explain the historical context of the production of the Haber process

Answer 16

Frtiz Haber produced in 1908 during WW1. German access to saltpetre (source of ammonia) from South America was blocked by allied forces. As a result, Germans were unable to make explosives or have fertiliser to produce food.
The Haber process was thus developed in order to produce a new way of forming ammonia.

Question 17

Identify the process of experiments used to identify cations in solution

Answer 17

1. Add HCl: if white precipitate forms, Pb is present
2. Add H2SO4: if white precipitate forms, can be Ba or Ca. Use flame test. Ba is apple-green, Ca is brick red.
3. Add NaOH: if blue precipitate, Cu. If brown precipitate, Fe3. If green then brown, Fe2.

Question 18

Identify the process of experiment used to identify anions solution

Answer 18

1. Add HNO3: if bubbles form, carbonate is present.
2. Add BaF: if precipitate forms, sulfate is present.
3. Add ammonia to make pH basic. Add more BaF. If precipitate forms, phosphate is present.
4. Add HNO3 to make pH acidic. Add Ag. If precipitate forms, chloride is present.

Question 19

What does AAS stand for?

Answer 19

Atomic Absorption Spectroscopy

Question 20

How does AAS work and what is is used for?

Answer 20

Used to detect trace elements (required in small amount on living organisms). Has allowed for the discovery of trace elements as AAS is sensitive enough to detect minute concentrations.
Sample is injected into a flame which atomises the sample.
Specific light is chosen which emits the specific emission spectrum of the particular element being tested. Amount of light absorbed by the photomultiplier is proportional to the amount of the element present.

Question 21

Outline the method in conducting flame tests to identify cations

Answer 21

1. Clean a piece of platinum wire
2. Dip wire into HCl sample.
3. Place wire into flame an record colour
   - Lead: blue
   - Calcium: red
   - Barium: pale green
   - Copper: blue/green
   - Iron (II): green
   - Iron (III): orange/brown

Question 22

Explain why acidifying the solution before introducing silver ions is necessary

Answer 22

Silver will react with oxygen in in basic solutions.

Question 23

Explain why levels of lead need to be monitored

Answer 23

There is no known level of lead that is considered safe.
Lead is bioaccumulative.
His levels can result in delays in brain and nervous system development. Increased risk of high blood pressure, kidney damage, neurological disorders, miscarriage or premature birth.

Question 24

Describe the method involved to measure the sulfate concentration of lawn fertiliser

Answer 24

1. Pour 0.1M nitric acid into fertiliser (removes carbonate and phosphate)
2. Filter insoluble material
3. Add barium ions slowly until precipitate forms
4. Filter off precipitate
5. Calculate the percentage mass of sulfate in fertiliser

Question 25

Identify the errors in the experiment which influence the reliability of the results and how they can be resolved

Answer 25

• not precise equipment
• not all fertiliser dissolved
• filter paper not dry
• sulfate left in beaker

Question 26

Identify the four layers of the atmosphere

Answer 26

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere (Ionosphere)

Question 27

Identify the chemical composition of the atmosphere

Answer 27

78% Nitrogen
21% Oxygen
0.9% Argon
0.037% Carbon Dioxide

Question 28

Describe the Troposphere

Answer 28

Layer closest to the Earth
Temperature decreases as altitude increases
90% of Earth’s gases

Question 29

Describe the Stratosphere

Answer 29

Second closest layer to the Earth
Temperature increases as altitude increases due to absorption of solar radiation by ozone molecules
Low pressure
9% on Earth's gases
Contains the ozone layer

Question 30

Identify the main pollutants found in the lower atmosphere, they source and impact on health

Answer 30

1. Carbon Monoxide: incomplete combustion of fossil fuels, volcanoes. Combines with Hb, refusing the amount of oxygen transported in the blood
2. Oxides of nitrogen: combustion in motor vehicles and power stations, lightning. Nitrogen dioxide causes breathing difficulties and lung irritation to nitrous and nitric acid.
3. Hydrocarbons: unburnt fuel. Carcinogenic, lung irritation.
4. Particulates: combustion of fossil fuels, smelting go metal ores, bush fires. Breathing problems, may be carcinogenic
5. Airborne lead: leaded petrol, smelting. Impaired mental function, nervous system delays.
6. Sulfur dioxide: smelting of sulphide ores. Irritation to throat and lungs, sulphurous acid.
7. Chloroflurocarbons: Pre-1996; refrigeration, air conditioning
8. Ozone: formed during photochemical smog. Irritates eyes and airways, increases asthma.

Question 31

Describe the nature of ozone as both a pollutant and a a UV radiation shield.

Answer 31

In the Troposphere: ozone is a pollutant produced by humans activity. Formed by intense sunlight on photochemical smog. Causes increased health risks; irritation to the eyes and air passages, asthma
In the Stratosphere: occurs naturally and acts as a UV radiation shield by absorbing low wavelength UV which can damage living cells. It is formed by the interaction of oxygen and UV.

Question 32

Describe the chemical structure of ozone

Answer 32

Ozone contains one regular covalent bond and a coordinate covalent bond. A coordinate covalent bond occurs when one atom provide both electrons which are shared between the two atoms.

Question 33

Compare properties of oxygen gas and ozone

Answer 33

Boiling Pt: BP of ozone is higher as it has a great molecular mass, meaning that there are stronger intermolecular forces, requiring more energy to break.
Solubility: oxygen is non-polar, so does not solubilise easily into water. Ozone is slightly polar, so will dissolve.
Chemical stability: Oxygen is more chemically stable than ozone as it requires less energy to break a coordinate covalent bond, than a double covalent bond.

Question 34

Compare the properties of oxygen gas and oxygen radical

Answer 34

Oxygen gas contains two oxygen atoms bound together by a double covalent bond. Oxygen radicals are a single oxygen atom with two unpaired electrons.
Oxygen radicals are highly reactive due to an incomplete outer shell. Will readily react with other atoms to achieve a complete outer shell. Oxygen gas is relatively stable.

Question 35

Identify the origins of CFCs and into atmosphere

Answer 35

CFC: type of haloalkane containing only chlorine, fluorine and carbon. Do not exist naturally.
Introduced in the 1930s as refrigerants as they were non-flammable, odourless and non-toxic. Continued use resulted in the release of CFCs into the atmosphere. Whilst they are non-toxic and inert, they are not destroyed by sunlight or oxygen. Thus, the accumulate and diffuse into the stratosphere, breaking down ozone.

Question 36

Identify the origins of halons in the atmosphere

Answer 36

Halons: types of haloalkanes containing containing carbon, bromine and other halogens.
They are dense, non-flammable and so are used in fire-extinguishers (bromotrifluoromethane)

Question 37

Describe the problems associated with the use of CFC and evaluate the effectiveness of methods to reduce their use

Answer 37

CFCs are can not be destroyed at low altitudes and are insoluble, so can’t be washed away by water. In the stratosphere, CFCs react with UV radiation, causing a chlorine atom to separate from the molecule. This chlorine atom reacts with ozone molecules, forming oxygen gas and ClO.
As the ozone becomes depleted, this allows more UV radiation to reach the Earth, resulting in increases in the risk of cancer, cataracts and sunburn.
Steps taken:
Montreal Protocol: international treaty in wich most countries agreed to lower their emissions of CFCs by 1996 and aims to also phase out use of HCFCs by early 21st century.
Introduction of alternative chemicals (HFCs).
As CFCs cannot be removed from the stratosphere, it is important that individuals wear sunscreen and use UV stabilisers in polymers to reduce breakdown of UV radiation.

Question 38

Identify the four technologies used to obtain information about ozone concentrations.

Answer 38

1. Ground-based Uv spectrophotometers. Measure the intensity of light absorbed by ozone and the wavelengths on either side. Intensities are then compared to give a measurement of the total ozone in there atmosphere per area of earth. Dobson Units (DU).
2. UV Spectrophotometers is balloons and aircrafts. Provide readings of ozone at different levels
3. Dobson spectrophotometers: measure stratospheric ozone above major cities
4. Spectrophotometers in polar orbiting satellites orbiting the earth.
   All technologies indicate a decline in the amount of ozone.

Question 39

Identify the two alternatives to CFCs and their effectiveness as an alternative

Answer 39

Hydrochloroflurorcarbons: contain fewer chlorine atoms. Rapidly oxidised in the troposphere, so fewer chlorine atoms reaching the stratosphere. Still destroys some ozone.
Hydroflurorcarbons: contains no chlorine atoms, so cannot form chlorine radicals. Does not cause ozone depletion. More expensive.

Question 40

Identify the factors to consider what determining water quality (Dean can totally annoy heartwarming teens)

Answer 40

• Dissolved oxygen and biochemical oxygen demand
• Concentration of common ions
• Turbidity
• Acidity
• Hardness
• Total dissolved solids

Question 41

Define Total dissolved solids and the healthy TDS value

Answer 41

The mass of solids dissolved in a unit of water. Healthy water has a TDS < 100mg/L

Question 42

Define disolved oxygen and the value in healthy water

Answer 42

Amount of oxygen dissolved in water from the atmosphere and from photosynthesising plants. 7-9mg/L

Question 43

Define biochemical oxygen demand (BOD) and the level in healthy water

Answer 43

measure of the concentration of dissolved oxygen needed for the complete breakdown of organic matter by aerobic bacteria. Healthy water has <5 ppm

Question 44

Identify factors that affect in concentration of common ions in water

Answer 44

• frequency of rainfall
• soil salinity
• effluents
• rate of river flow
• evaporation rates
• temperature of water

Question 45

Assess the effectiveness of methods used to purify water

Answer 45

Filtration is effective in removing large particulates after flocculation. Yet smaller particles may still pass. Chlorination is effective in killing disease-causing pathogens. However, these methods cannot guarantee that pure water reaches residential areas (sewerage leaks etc). Giardia and Cryptosporidium scare in 1998.
Membrane filters are more effective, yet more expensive.
Methods to improve the effectiveness include:
- monitoring at every stage and taking regular samples
- microbiological testing
- public health reporting

Question 46

Describe the structure of membrane filters and explain how the purify water.

Answer 46

Membrane filters are a thin film of synthetic polymer with small pores in a uniform size. The film in pleated to form a cartridge that can be replaced and reused.
Used to treat drinking water and sewerage for reuse. Designed to remove solutes, colloidal particles and microorganisms. Water flows across the membranes to avoid particulates blocking the pores.
The smaller the pore size, the more expensive the filter.
Advantages:
- filter small particles
- strong
- cleaned and rested.

Question 47

Identify qualitative and quantitative tests to analyse the purity of water (Dean can totally annoy heartwarming teens)

Answer 47

Disolved oxygen: meter and an oxygen probe
Common ions: AAS or use of other chemicals
Turbidity: turbidity tube
Acidity: pH probe and data logger
Hardness: titration with EDTA (calcium has 1:1 ratio with EDTA)
Total dissolved solid: data logger with conductivity probes.

Question 48

Describe tests used to identify heavy metal pollution in waterways

Answer 48

Heavy metals are the transition metals and lead. Must be monitored has they are toxic to humans.
The accumulate in aquatic organisms, which humans consume (bioaccumulation).
Tests:
- place sulfate ions in water, Pb, Cu, Mercury form black precipitates, Cadmium forms yellow precipitate.
- AAS
- Volumetric and gravimetric analysis

Question 49

Describe tests used to monitor possible eutrophication in waterways

Answer 49

Eutrophication is the process in which a water body becomes enriched with nutrients that results in excessive growth of aquatic plants. Due to the presence of nitrates and phosphates. Results in the reduction in the amount of sunlight reaching deep water plants, therefore resulting in oxygen depletion.
Tests:
- disolved oxygen
- monitoring phosphate levels (calorimetry)
- monitoring nitrate levels (calorimatrically)

Question 50

Describe the Woronora Dam in terms of:

• Possible sources of contamination
• Chemical tests
• Physical tests
• Chemical additives

Answer 50

• Contamination: faecal, longwall mining can lead to surface cracking resulting in contamination of water, release of methane gas, ash and increased siltation
• Chemical tests: to test for individuals cations and anions
• Physical tests: screening/flocculation and sedimentation/sand filtration/sanitisation/pH adjustment
  Flocculation: add Aluminium hydroxide to make water basic and Iron (III) chloride to form large particles.
  pH adjustment: addition of ammonia to produce chloramines that maintain disinfection of chlorine.
• Chemical additives: fluoridation to strengthen tooth enamel to minimise tooth decay.