Chemistry Marathon (1 Viewer)

[powlmao]

Someone should create a marathon thread in the Physics and Chem forums.

First question What is CFC's impact on the ozone.

lol i don't even do chem

 

[jamesfirst]

It depletes it. Next question:


What is the enzyme used to create a named biopolymer?

 

[_deloso]

It depletes it. Next question:


What is the enzyme used to create a named biopolymer?

Alcaligenes Eutrophus? if my memory serves me right...

next question: Assess ethanol as an alternative car fuel and evaluate its success as a car fuel.

 

[someth1ng]

Assess ethanol as an alternative car fuel and evaluate its success as a car fuel.

I'm in Year 11 so I'm not 100% sure but I go along the lines of:
- Ethanol is a renewable source which is in turn, better for the environment especially when compared to fossil fuels and petroleum which are limited in supply.
- This use of Ethanol will help prolong the life of petroleum.
- Ethanol is extracted from sugars in plants generally crops.
- It is currently in use in the present day but only in small proportions as shown in "E10" variations of fuel.
- 100% Ethanol is unlikely due to limitations of machines/engines using Ethanol due to its corrosive nature.
- 100% Ethanol will need a totallly new architecture to both manufacture the engines and the manufacturing process itself would need to be updated.
- The usage of Ethanol will result in much less pollutants since the release of the CO2 is equal to the amount absorbed by the crops which produce Ethanol.
- The cost of using Ethanol is also higher but it is subsidised to reduce the cost on the consumer end to promote the use of E10 fuels.
I'm assuming that this is worth about 4 marks.

 

[jamesfirst]

Alcaligenes Eutrophus? if my memory serves me right...

next question: Assess ethanol as an alternative car fuel and evaluate its success as a car fuel.

Ethanol is a renewable fuel that can be produced by the fermentation of glucose to produce ethanol and water. Yeast is required to consumed the glucose and must be carried out in a low oxygen concentrated and 30-40 degrees area.

Ethanol is said to be renewable as glucose is a renewable monomer from a condensation polymer cellulose. Cellulose can be broken down with cellulases enzyme to produce glucose. Furthermore, the fermentation reaction produces a carbon dioxide which can participate in photosynthesis reaction to produce glucose.

Ethanol is very friendly to the environment due to its nature of complete combustion. It undergoes complete combustion due to the presence of oxygen, hence is both friendly to the environment, but also produces carbon dioxide that can also participate in photosynthesis.

In the contemporary society, countries such as Brazil and Australia has promoted in using ethanol based fuels in order to reduce greenhouse gases and a way of substituting harmful and non-renewable fossil fuels. Many petrol stations have started using e10 ethanol based fuels while Brazil has designed a car engine that is purely ran by ethanol fuel. However, the numbers have decreased due to the price of its production.

Advantages:
- Renewable
- Environmentally friendly

Disadvantages:
- Car engines which doesn't support ethanol fuel must be replaced.
- Ethanol fuels are more expensive to produce than synthetic fuels.


Next question: From several records, it has shown that ozone levels have decreased. Explain how the ozone is both friendly and deadly to the society and evaluate how ozones are destroyed and identify any replacement products that is more advantageous.

 

[InVinsanity]

from several records, it has shown that ozone levels have decreased. Explain how the ozone is both friendly and deadly to the society and evaluate how ozones are destroyed and identify any replacement products that is more advantageous.

Ozone in the troposphere acts as a pollutant, it contributes to photochemical smog which doesnt look good, but more importantly because ozone is a strong oxidant causes headaches, breathing difficulties and can aggravate respiratory problems. In the stratosphere ozone acts as UV radiation shield, it works in its cycle. Ozone in the presence of UV-B and occasional UV-C rays breaks up the ozone molecules

O3 --> O2 + O• which can also go O2 --> O• + O•, finally the ozone free radicals and oxygen molecule combine to make ozone again O• +O• --> O2, O2 + O• --> O3. This is the ozone cycle.
CFC's (chlorofluorocarbons) were initially used in aerosol propellants and fire extinguishers, because they are highly inert they do not decompose in the troposphere. CFC's slowly rise into the atmosphere and begin seeping into the stratosphere, where the decompose under the presence of UV light.
CFC11 CFCl3 --> CFCl2 + Cl•. This chlorine free radical interacts with oxygen free radical, that was created from the ozone cycle and disrupts the cycle. insert equation.
The Montreal Protocol, was used to the eliminate the use of CFC's, and were replaced by HCFC the hydrogen in the molecule, allows it to decompose in the troposphere but they still do stand a chance in preventing ozone depeletion. HFC were introduced they have no potential in depleting ozone but scientists believe they contribute to the green house effect.

That was massive, not concise enough, please criticise.
How is ozone measured and explain the methods used?

 

[jamesfirst]

That was massive, not concise enough, please criticise.
How is ozone measured and explain the methods used?

Good but I think I would have given 5-6/7 just because you didn't write the full ozone-depletion equations


I don't think that question required the Montreal Protocol (to be honest, I think you would have ran out of room). Otherwise, nice job. Think it would be a nice full mark if you added every equations there are.


How is ozone measured and explain the methods used?

Not really good at this ;S..


Ozones are measured by 3 types of measuring instruments: Ground, balloon and satellite based spectrophotometers.

Ground-based measuring device include the UV spectrophotometers which measures the amount of UV radiation observed by the ozone in order to calculate the concentration of ozones in the stratosphere.

Balloon-based = I don't know

Satellite-based measuring device include the Total Mapping Ozone Spectrophotometers (TOMS) which measures the total concentration of ozones in the entire atmosphere by it's thickness. It measures it in Dobson units.

Not too strong on this... perhaps share your response also



Next question:

Describe how ethanol can be derived from a sugar cane.

 

[InVinsanity]

Describe how ethanol can be derived from a sugar cane.

The sugar cane, is used for its purpose, the (whatever the sugar cane is made out of) biomass, undergoes acid digestion, or enzyme digestion which breaks the cellulose molecule in glucose monomers (C6H1206). The glucose is then made into a solution, where it is, yeast is added no air and moderate temperatures.
C6H12O6 --> 2C2H6O + 2CO2, the ethanol is then distilled. This is a exothermic reaction, so heat is created, if it gets too warm then the yeast will die. The yeast secretes an enzyme zymases which catalyses the reaction of glucolysis producing carbon dioxide and ethanol from glucose.


Define the term buffer, and outline a buffer in the blood.

 

[UnrealAnchovies]

Define the term buffer, and outline a buffer in the blood.

a buffer is a solution of a weak acid and its conjugate base (or other way around) which works to maintain a stable pH despite additions of base/acid

the bicarbonate ion in the human blood acts as a buffer for incoming carbon dioxide, which can mildly affect enzyme reactions within the body.

HCO3-(aq) + H+(aq) CO2(g) + H2O(l)

If the system becomes acidic, equilibrium shifts left to increase the pH.

there's moar but im not motivated enough to continue.

-----

Briefly describe how AAS works

 

[b3kh1t]

Define the term buffer, and outline a buffer in the blood.

a buffer is a solution of a weak acid and its conjugate base (or other way around) which works to maintain a stable pH despite additions of base/acid

the bicarbonate ion in the human blood acts as a buffer for incoming carbon dioxide, which can mildly affect enzyme reactions within the body.

HCO3-(aq) + H+(aq) CO2(g) + H2O(l)

If the system becomes acidic, equilibrium shifts left to increase the pH.

there's moar but im not motivated enough to continue.

A buffer solution has comparable amounts of a weak acid and its conjugate base, this will form an equilibrium at a certain pH and will thus resist be able to maintain an approximately constant pH, even by the addition of significant amounts of strong acids or strong bases.
actually the buffer in blood is but due to changing concentrations in carbon dioxide other buffers are need and the most predominate buffer in the blood is therefore haemoglobin. It is amphiprotic allowing it to act as a buffer, but strictly speaking it is a weak base. By noting haemoglobin as Hb, the following equation demonstates its buffering abilities;

 

[b3kh1t]

Briefly describe how AAS works

AAS is extremely sensitive and can detect concentrations of elements at the parts per millions and even parts per billion concentrations. This process works by spraying a sample mixture into the flame which vaporises the atoms while a specific beam of light is used to determine the concentration of a specific cation present is passed through the vapour. The atoms will absorb some of this light and the rest is passed through and concentrated by a monochromator, where the beam is received and analysed by a detection device. Several standard solutions of the specific element being tested is made and tested for, the amount of light absorbed for these different solutions is plotted against there concentrations, forming a calibration. curve.

 

[Some Vunt]

Alcaligenes Eutrophus? if my memory serves me right...

I thought that was the bacteria not the enzyme.

 

[UnrealAnchovies]

I thought that was the bacteria not the enzyme.

it is the bacteria

---

you guys have to post questions after answering them

but anyways, compare the effects on the environment of either the LEAD-ACID CELL OR DRY CELL with a cell of your own choosing (you know the list)

 

[b3kh1t]

it is the bacteria

---

you guys have to post questions after answering them

but anyways, compare the effects on the environment of either the LEAD-ACID CELL OR DRY CELL with a cell of your own choosing (you know the list)

lol I don't have any questions now so what do you want me to ask, and to answer your question.

The dry cell also had a very large affect on society as it was one of the first portable batteries to be produced which allowed it to make torches, radios, toys and clocks to be portable. However, the disadvantages for dry cells are it does not produce high currents for its size and it may develop leaks as the zinc casing corrodes. As a result, the dry cell batteries are harmful to the environment only in the sense that it releasing hazardous material and is creating waste material.

The Button Cell is more expensive than the dry cell. The battery has had a big impact on society especially as it is non-toxic and can be used inside the body. Therefore, the button is much better than the dry cell as it does not produce any hazardous materials that will harm the environment.

Even though fuel cells are not being used widely throughout society they are predestined for use in motors and appliances, especially as it has an extremely high efficiency rate. Also the fuel cell is very environmentally friendly as it has only water and heat as its emissions, as a pose to dry cells with contain hazardous materials.

The fact that both electrolytes are the same element will mean that waste disposal will be very minimal unlike the dry cell where leakages will ruin the battery. Also the life cycle of the Vanadium Redox battery is very long in relation to the dry cell therefore meaning the Vanadium Redox is a better battery.

The improvement of the Lithium battery over the dry cell has had a large affect on society as it provided longer lasting and rechargeable batteries which is very useful, specifically in the medical appliances. However, lithium is harmful to the environment and must be carefully disposed of to prevent any environmental damage.

The Gratzel cell uses the natural light from the environment to generate the electricity, although it still has hazardous waste material that is harmful to the environment, causing a similar effect to that of the dry cell.

 

[b3kh1t]

Good but I think I would have given 5-6/7 just because you didn't write the full ozone-depletion equations


I don't think that question required the Montreal Protocol (to be honest, I think you would have ran out of room). Otherwise, nice job. Think it would be a nice full mark if you added every equations there are.


How is ozone measured and explain the methods used?

Not really good at this ;S..


Ozones are measured by 3 types of measuring instruments: Ground, balloon and satellite based spectrophotometers.

Ground-based measuring device include the UV spectrophotometers which measures the amount of UV radiation observed by the ozone in order to calculate the concentration of ozones in the stratosphere.

Balloon-based = I don't know

Satellite-based measuring device include the Total Mapping Ozone Spectrophotometers (TOMS) which measures the total concentration of ozones in the entire atmosphere by it's thickness. It measures it in Dobson units.

Not too strong on this... perhaps share your response also



Next question:

Describe how ethanol can be derived from a sugar cane.

The balloon devices used to measure ozone do so in a very similar way to the satellites. The balloon achieves this high height as they fill it with helium which is the lightest gas (hydrogen is lighter but it diatomic while helium is a noble gas). These devices measure the amount of ozone in the Dobson Units and this refers to the amount of ozone between the device and the ground at sea level (the normal amount of ozone is 300 DU which translates to 3 mm of ozone). Once the amount of ozone is measured, the TOMS (Total Mapping Ozone Spectrometers) send the information to the chemists on the ground.

 

[OmmU]

Cellulose from sugar cane is hydrolised to form glucose. Glucose is then fermented to ethanol:

C6H12O6(aq) ---> 2CO2 (g) + 2C2H5OH (aq)

Yeast is used as a catalyst, around 27C, oxygen is excluded to prevent yeast from reproducing, ethanol should be removed through distillation as >10% ethanol concentration can kill the enzymes in yeast used to catalyse the reaction.


NEXT QUESTION:

A sample of water was suspected to contain Cl- ions. Describe a chemical test that could be used to test for the presence of these ions. Include a chemical equation.

 

[b3kh1t]

Cellulose from sugar cane is hydrolised to form glucose. Glucose is then fermented to ethanol:

C6H12O6(aq) ---> 2CO2 (g) + 2C2H5OH (aq)

Yeast is used as a catalyst, around 27C, oxygen is excluded to prevent yeast from reproducing, ethanol should be removed through distillation as >10% ethanol concentration can kill the enzymes in yeast used to catalyse the reaction.


NEXT QUESTION:

A sample of water was suspected to contain Cl- ions. Describe a chemical test that could be used to test for the presence of these ions. Include a chemical equation.

Just to add to your information, the breakdown of cellulose into glucose does not occur naturally and actually requires the use of cellulase enzymes.

To test for Cl- ions in a solution, add silver nitrate or lead nitrate and if a precipitate forms chloride ions are present (the only insoluble chlorides are silver chloride and lead chloride).
NB: you must test for the absence of sulfate, carbonate and phosphate ions as a precipitate may also form.

 

[HyperComplexxx]

What is a buffer solution? Provide an example on how it works with relevant equations

 

[b3kh1t]

What is a buffer solution? Provide an example on how it works with relevant equations

A buffer is a solution with comparable amounts of a weak acid or weak base and its conjugate base or acid, this will form an equilibrium at a certain pH and will thus be able to maintain an approximately constant pH, and can resist the addition of significant amounts of strong acids or strong bases.

An example of a buffer is in the human body. Many processes in the human body are pH sensitive and operate only through narrow pH ranges. The kidneys purify the blood by removing metabolic waste products, many of which are acids. Because the kidneys have to dispose of these acidic wastes without producing an excessive low pH, a dihydrogen phosphate - hydrogen phosphate buffer is used (pH of about 6.2-8.2). The acidic waste will form with the hydrogen phosphate and be excreted in the urine.

 

[b3kh1t]

I thought some of you might find this helpful! They are questions and answers on the 2nd part of production of materials ( i.e. cellulose + Bio polymers)

That is really good, much appreciated =D