Predictions for Chemistry 2014 HSC? (6 Viewers)

[seventhroot]

easiest solution

> don't do chemistry

 

[Queenroot]

yeah agreed

no but I mean IUPAC changed their naming methods looool gg

IUPAC wouldn't have changed their methods. A lot of people just don't know how to name properly (aka teachers). The point of IUPAC is to have no discrepancies.
I am part of the ~ IUPAC naming master race ~

 

[seventhroot]

yeah you should have told me this in year 10 when I was picking my subjects

silly square

> still continues it for the HSC

 

[enigma_1]

good answer, but I think its important to talk about vertical mixing (or lack thereof) between the tropo and stratospheres in particular because this forms the foundations of all the ozone stuff, telling markers you know about the topic holistically

Yes definitely this Added into my feedback also

 

[zhertec]

no even that, they changed it Adrita

though seriously because there is so much discrepancy as to how it is taught across schools, I've heard that they give compounds where its possible to get the same name with either method

Okay next question: Compare the processes of thermal and catalytic cracking (4 marks)

Similarities:
- Both processes require energy in order to crack the hydrocarbon into smaller chains.
-Ethene is formed as a result of large hydrocarbon chains are cracked.

Differences:
- Thermal cracking of hydrocarbons result in free radical hydrocarbons, which are cracked to obtain ethene gas, in which the free radicals reform and are recycled to be further cracked. While catalytic cracking utilises a porous zeolite (aluminiun silicate) having a high internal surface area where the chain is cracked, this process does not produce free radical hydrocarbons.
- Catalytic cracking occurs at much lower temperatures ~500 degrees, while in thermal cracking the pyrolysis coils reach around 750-900 degrees, hence catalytic cracking saves more energy than thermal cracking.

 

[enigma_1]

IUPAC wouldn't have changed their methods. A lot of people just don't know how to name properly (aka teachers). The point of IUPAC is to have no discrepancies.
I am part of the ~ IUPAC naming master race ~

omg tell me about it, the teachers at our school can't even explain it properly :/

 

[SuchSmallHands]

no even that, they changed it Adrita

though seriously because there is so much discrepancy as to how it is taught across schools, I've heard that they give compounds where its possible to get the same name with either method

Okay next question: Compare the processes of thermal and catalytic cracking (4 marks)

Cracking is the process by which longer chain alkanes can be decomposed into smaller chain alkanes and alkenes in order to align relative production with relative demand. In catalytic cracking, aluminosilicate zeolite catalysts are used in order to decompose hydrocarbon chains at 500oC in the absence of oxygen. In thermal cracking, temperatures of 700-1000oC are used to decompose the chains as they pass through heated metal at 7,000 kPa pressure.

Sorry, I know this isn't enough for four, but I answered this properly before and I'm lazy.

Assess the potential of Ethene as a raw material in industry (five marks)

 

[enigma_1]

Similarities:
- Both processes require energy in order to crack the hydrocarbon into smaller chains.
-Ethene is formed as a result of large hydrocarbon chains are cracked.

Differences:
- Thermal cracking of hydrocarbons result in free radical hydrocarbons, which are cracked to obtain ethene gas, in which the free radicals reform and are recycled to be further cracked. While catalytic cracking utilises a porous zeolite (aluminiun silicate) having a high internal surface area where the chain is cracked, this process does not produce free radical hydrocarbons.
- Catalytic cracking occurs at much lower temperatures ~500 degrees, while in thermal cracking the pyrolysis coils reach around 750-900 degrees, hence catalytic cracking saves more energy than thermal cracking.

Cool, and you should probs explain the processes briefly beforehand and yeah should be good

 

[SuchSmallHands]

good answer, but I think its important to talk about vertical mixing (or lack thereof) between the tropo and stratospheres in particular because this forms the foundations of all the ozone stuff, telling markers you know about the topic holistically

I sort of skipped over a lot of the atmosphere stuff, what do you mean about the vertical mixing? The way ozone takes ages to move upward? Can you give an example of how you would write it please?

 

[enigma_1]

Story of my life with most of my subjects

ahah srs our science department is so fkn shit don't even get me started. They can't even teach properly

 

[enigma_1]

I sort of skipped over a lot of the atmosphere stuff, what do you mean about the vertical mixing? The way ozone takes ages to move upward? Can you give an example of how you would write it please?

Something sort of like this

This is an ugly question.

The troposphere is within the sea level to 10km range. Here temperatures are at its lowest in comparison to the other spheres and this is where nitrogen is the predominant gas, making up 78% of the atmosphere, followed by oxygen (20%) and then argon B] temperature decreases with altitude and there is presence of convection currents which mix the gases of the troposphere including N2, O2, H2O, CO2, Ar gases)[[/B]. The troposphere is where pollutant gases may be formed through human activity such as ozone which is dangerous as it is an irritant, however in the stratosphere (second atmospheric layer) ozone is of a benefcial advantage to us humans as it forms a barrier, preventing strong UV rays UV-B AND UV-C from entering into the troposphere and causing cataracts along with an increase in skin cancer whilst UV-A is let through which is beneficial for photosyntheisis and promotes formation of vitamin D on skin. Stratosphere is approximately 15-50km above sea level and temperature increases with altitude and there is less vertical mixing of gases here whilst there is presence of some convection currents, hence pollutants which enter the stratosphere remain there for a long time, because the gases don't really mix much. The mesosphere is 50-85km where there is barely any gases but has a few gas particles that would not exist in the previous spheres, and the temperature is higher than that of the isn't the temperature really low here? It's -100 degrees Celsius and temperature decreases with altitudestratosphere and troposphere because here there are strong UV rays and no ozone to shield it. Thermosphere as its name suggests is the hottest 85km +, barely any gases or particles present due to the heat temperature 1700 degrees celsius. and the ionosphere also exists somewhere here where there is presence of gaseous ions of molecules such as O2+, O+, NO+ and temperature increases with altitude and the air is also really thin here

 

[SuchSmallHands]

Something sort of like this

Yeah, I never did any of that oops haha. Thanks Enigma

 

[enigma_1]

Yeah, I never did any of that oops haha. Thanks Enigma

ahah no worries )

 

[enigma_1]

our actual chem teacher isn't back till next week cause of some mission trip in India lol. and our substitute can only teach the previous syllabus gg

omg are you serious? I feel for you man :/

teachers love leaving students during hsc year. The number of teachers who do this at my school *facepalm*

 

[Beterban]

can you give me a definition for each of these and a method to measure them
my notes are a bit dodgy

 concentrations of common ions:
 total dissolved solids:
 hardness:
 turbidity:
 acidity:
 dissolved oxygen and biochemical oxygen demand

 

[Queenroot]

omg are you serious? I feel for you man :/

teachers love leaving students during hsc year. The number of teachers who do this at my school *facepalm*

Omg agreed, the level is too damn high. They all get PREGNANT.

Btw do you know Bragg died recently?

 

[SuchSmallHands]

Omg agreed, the level is too damn high. They all get PREGNANT.

Btw do you know Bragg died recently?

Two of my senior teachers got pregnant. Do not approve.

 

[seventhroot]

ahah srs our science department is so fkn shit don't even get me started. They can't even teach properly

at least you have a science department

 

[enigma_1]

Omg agreed, the level is too damn high. They all get PREGNANT.

Btw do you know Bragg died recently?

ahahah ikr

OMGGGG SERIOUSSSSSS???????? How did you find out?????

 

[seventhroot]

ahahah ikr

OMGGGG SERIOUSSSSSS???????? How did you find out?????

http://en.wikipedia.org/wiki/William_Lawrence_Bragg

he's been dead for a while