The better chemistry game (1 Viewer)

[MuffinMan]

The thing you have to do is to answer a dot point and each person answers the next one etc..

I'll start off

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

Burhan Gemikonalki is a Plant Chemist at Qenos, a major chemical manufacturing company that makes ethylene from ethane then polymerises it to polyethylene.

Burhan’s job at Qenos has several components

- monitoring the quality of ethylene and propylene products from the plant to ensure that they meet the requirements for the next stage of manufacture: in particular determining the nature and amount of impurities present;
- monitoring waste water from the Qenos complex to ensure that it meets the environmental requirements (such as pH, suspended solids, sulfate, grease, hydrocarbons) before it is discharged; and
- collaborating with the process engineers at the cracking furnace (ethane to ethylene) to adjust the operating conditions in order to optimise product yields.

The chemical principles involved:

are adsorption (for gas-solid chromatography) and solubility (for GLC)

If the stationary phase is solid, then the components of the mixture adsorb onto it (stick onto the surface) to differing extents, pass through the column at differing rates and so are separated. A device at the end of the column detects each substance as it passes out of the column and measures it quantatively.
If the stationary phase is liquid, then the components of the mixture dissolve in it to differing extents. The more soluble a substance is in the stationary liquid, then the slower the substance moves through the column (tube). Hence a separation is effected and the detector measures the amount of each component as it emerges from the column. Polarity of molecules is often a key factor in GLC separations: if the stationary phase is a polar liquid, then the more polar a component of a mixture to be analysed, the greater is its solubility and so the more slowly it moves through the column.

[Ref: Conquering Chemistry, 3rd ed., p188-189]

 

[Jumbo Cactuar]

1.2 identify the need for collaboration between chemists as they collect and analyse data

There is no I in team, duh! Next!


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

The combustion reaction of petrol in car engines is dramatically altered with variation of the oxygen levels in the reaction mixture.

Hydrocarbons are ideally combusted to form only water and carbon dioxide. Limiting oxygen gives rise to the production of carbon monoxide and soot. Whilst carbon dioxide has enviromental impacts, carbon dioxide is highly toxic and is undesireable. Solid soot would undoubtably lead to serious mechanical malfunction is large quantities. Carbon dioxide production releases the most energy from the combustion and is more efficient. Too high a concentration of oxygen could lead to a greater resistance on the pistons (minor I know).

CO is toxic due to its affinity to heamoglobin, preventing the body from successfully tranferring oxygen throughout the body.

Exhaust systems of most vehicles are fitted with an oxygen sensor made from zirconia and platinum. The data from this sensor controls the fuel injection system, which maintains optimum air/fuel mixture.

 

[MuffinMan]

2.1 Identify and describe the industrial uses of ammonia

Ammonia is used to make:

- fertilisers (sulfate of ammonia, ammonium nitrate, urea)
- fibres and plastics (rayon, acrylics, nylon)
- nitric acid, which in turn is used to make fertiliser (ammonium nitrate), dyes, fibres, plastics, and explosives such as ammonium nitrate , TNT (trinitrotoluene) and nitro-glycerine (in dynamite)
- household cleaners
- detergents (non-ionic ones)

By the beginning of the twentieth century there was a growing need for an industrial method of synthesising ammonia. Increasing demands for nitrogenous fertiliser to grow food for increasing world populations were placing strains on the supply of the naturally-occuring Chile saltpetre (sodium nitrate), the main ‘artificial’ fertiliser at that time. In addition the growing militancy of Germany was promoting calls for more explosives (generally made from nitric acid which in turn was mainly produced from saltpetre).

 

[physician]

2.2 identify that ammonia can be synthesised from its component gases, nitrogen and hydrogen:

Ammonia can be synthesised from its component gases, nitrogen and hydrogen.

Ammonia is prepared from its elements (nitrogen and hydrogen) via a catalytic reaction known as the Haber process. The reaction is an example of a reversible exothermic equilibrium:

N₂ + 3H₂ <---> 2NH₃ delta H = -92 KJ


Under pressure and heat, nitrogen and hydrogen react in the ratio of 1 volumes of nitrogen to 3 volumes of hydrogen to produce 2 volumes of ammonia...

 

[physician]

sorry I'm just really bored so i hope u guys don't mind me going onto the next dot pt...

2.3 describe that synthesis of ammonia occurs as a reversible reaction that will reach equilibrium

The synthesis of ammonia occurs as a reversible reaction. This means that ammonia is formed from nitrogen and hydrogen (the forward reaction) and once some ammonia is produced, some nitrogen and hydrogen are formed from the ammonia (the reverse reaction). When nitrogen and hydrogen are initially added to a reaction vessel, the reaction is slow. Equilibrium is reached when the rate of the forward recation is the same as the rate of the reverse reaction.

I Hope that's sufficient enough

 

[Jumbo Cactuar]

2.4 identify the reaction of hydrogen with nitrogen as exothermic

...hmmmm....

2.5 explain why the rate of reaction is increased by higher temperatures

For a reaction to occur there needs to be a collision of molecules having enough energy to react. Increasing the temperature increases the mean kinetic energy of the system slightly. Due to the Maxwell-Boltmann distribution of molecular energies for gases, a large disproportional quantity of molecules have enough energy to react (larger than the activation energy). Furthermore, the molecules are vibrating at a frequency proportional to the square root of the absolute temperature (less important factor), so an increase in temperature increases the rate of collision. Since the a larger proportion of molecules have enough energy to react, for every collision of molecules there is an increased probability of a reaction. Thus the rate of reaction is increased.

2.6 explain why the yield of product in the Haber process is reduced at higher temperatures using Le Chatelier’s principle

Ammonia production is exothermic.

Heat is produced on reaction.

Increasing the heat opposes the forward reaction.

Reactants favoured, yield decreased.

 

[rnitya_25]

2.7 : Explain why the Haber Process is based on a delicate balancing act involving reaction energy, reaction rate and equilibrium.

The Haber Process is based on a delicate balancing act between meeting the requirements for reaction rate, reaction energy and equilibrium. The reaction energy of the system and the reaction rate prefer high temperatures(reaction energy requirements are not met at lower temperatures). Equilibrium however favours a lower temperature as the reaction is exothermic. An increased temperature will shift equilibrium towards reactants. A decreased temperature will not make the reaction occur.

2.8 : Explain that the use of a catalyst will lower the reaction temperature required and identify the catalyst used in the Haber Process.

The catalyst used is finely ground porous iron oxide and this is used because the fact that it is porous provides a surface area for the reaction to occur in. The catalyst not only speeds up the reaction rapidly but also lowers the activation energy required. It also enables the reaction to occur at lower temperatures.

 

[Abtari]

2.7 : Explain why the Haber Process is based on a delicate balancing act involving reaction energy, reaction rate and equilibrium.

The Haber Process is based on a delicate balancing act between meeting the requirements for reaction rate, reaction energy and equilibrium. The reaction energy of the system and the reaction rate prefer high temperatures(reaction energy requirements are not met at lower temperatures). Equilibrium however favours a lower temperature as the reaction is exothermic. An increased temperature will shift equilibrium towards reactants. A decreased temperature will not make the reaction occur.

im confused with this dotpt...can someone explain? how is it a "balancing act"

 

[The_highwayman]

Well, basically, with an increased amount of heat, The reaction rate is INCREASED but the amount of product is DECREASED because of equilibrium (ammonia production is exothermic)

Therefore, ammonia production via the Haber process is a delicate balancing act to ensure plenty of PRODUCT in an economical amount of TIME (ammonia is most often made for commercial/industrial purposes and is therefore sold.)

The delicate balance is a compromise between economics and chemistry.

 

[Dreamerish*~]

2.9 Analyse the impact of increased pressure on the system involved in the Haber process.

In accordance to Le Chatelier's principle, increasing the pressure favours the production of ammonia because two molecules of gaseous ammonia occupy a smaller volume than the four molecules of gaseous reactants:

N_2(g) + 3H_2(g) 2NH_3(g)

High pressure also increases the reaction rate because the gas molecules are closer and at higher concentrations. However, high-pressure equipment is expensive and requires considerable energy to operate.

To achieve an economic yield of about 30%, a pressure of 35 000 kPs (35 MPa or 345 atm) is used.

Is it really better than mine? Is it really?

 

[richz]

2. 10 explain why monitoring of the reaction vessel used in the Haber process is crucial and
discuss the monitoring required
Temperature and total pressure must to monitored to make sure optimum efficiency is
maintained
The composition of incoming gasses must be monitored
− make sure there is no 2 O since it may cause explosion
− make sure there that the ratio of the 2 H to 2 N is kept at 3:1 so that there is no build
up of excess reactant
− make sure there is no carbon monoxide since it will poison the catalyst
− build up of uncreative gasses such as argon or methane can reduce the efficiency of
the conversion
- using high pressure, may cause explosions too, so monitoring is also required
- monitor the temp so not too high, or it will dmg the catalsyt
- Also make sure the surface area of the catalyst is clean so efficient absorption can occur

 

[Sirius Black]

Best chem game ever!

1.4 Gather, process and present information from secondary sources about the work of practising scientists identifying:
-the variety of chemical occupation
Analytical: measurement of concentrations
Biomolecular: protein structure
Cereal: protein in grains
Chemical education: learning of chemicals
Colloid and surface science: improving detergent action
Electrochemistry: chemical batteries
Environmental:Air pollution; N in water
Industrial: production efficiency
Inorgainic: minerals
Organic: petrol chemicals
Physical: physical properties and changes
Polymer: properties of plastics
Solid State: silicon solar cells and chips
-a specific chemical occupation for a more detailed study
For example, environmental chemists are often employed by government agencies. This type of chemist could be involved in monitoring air and water quality and interpreting data to provide policy advice to statutory authorities. The chemist would have a B.Sc, followed by postgraduate qualifications in fields such as scientific communication or management. This chemist would have a good underlying knowledge of chemical concepts, particularly in chemical analysis, including separation techniques and spectrometry.