Predictions for Chemistry 2014 HSC? (10 Viewers)

[Sinyeta]

hnnnnng sevenroots? his name seem like he is very very sex indded thank you

 

[zhertec]

It would be something weird, you wouldn't be able to say that there are three carboxylic acid functional groups attached though, because the carbon is part of the main chain now.

Agreed as that would state only the position of the carboxylic acid, though if you add in the tri carboxylic that might work, cause I heard somewhere that IUPAC was now making it in alphabetical order or something for the names...I might be wrong though..

 

[SuchSmallHands]

Agreed as that would state only the position of the carboxylic acid, though if you add in the tri carboxylic that might work, cause I heard somewhere that IUPAC was now making it in alphabetical order or something for the names...I might be wrong though..

Nooppee, there's only one carboxylic acid functional group left attached if you take the other two carbons into the main chain. This isn't going to go anywhere though, I know I don't know enough about naming organic compounds to offer and alternative, so back to questions

Explain how the structure and properties of polyethylene and polystyrene relate to the way each is used. (4 marks)

 

[pheelx3]

It would be something weird, you wouldn't be able to say that there are three carboxylic acid functional groups attached though, because the carbon is part of the main chain now.

yeah then it would be 3-carboxy-3-hydroxypropane-1,2-dicarboxylic acid or otherwise better known as 3-carboxy-3-hydroxypentanedioic acid
but PLEASE NO ONE WRITE THAT FOR YOUR HSC.
IT WAS JUST SOMETHING I WAS THINKING OF LOL

Agreed as that would state only the position of the carboxylic acid, though if you add in the tri carboxylic that might work, cause I heard somewhere that IUPAC was now making it in alphabetical order or something for the names...I might be wrong though..

^ sorry but that's unrelated
It never was name from the most electronegative end (which the 2012 HSC did and which conquering did).
I think it was just an old (unofficial) convention that existed among the older scientists

 

[SuchSmallHands]

yeah then it would be 3-carboxy-3-hydroxypropane-1,2-dicarboxylic acid or otherwise better known as 3-carboxy-3-hydroxypentanedioic acid
but PLEASE NO ONE WRITE THAT FOR YOUR HSC.
IT WAS JUST SOMETHING I WAS THINKING OF LOL



^ sorry but that's unrelated
It never was name from the most electronegative end (which the 2012 HSC did and which conquering did).
I think it was just an old (unofficial) convention that existed among the older scientists

Where are you getting the two carboxylic acid functional groups from? (then pllss stop this massive derail haha)

 

[pheelx3]

Nooppee, there's only one carboxylic acid functional group left attached if you take the other two carbons into the main chain. This isn't going to go anywhere though, I know I don't know enough about naming organic compounds to offer and alternative, so back to questions

Explain how the structure and properties of polyethylene and polystyrene relate to the way each is used. (4 marks)

PE comes in two forms LDPE and HDPE. LDPE is a highly amorphous solid, allowing it to be transparent and very flexible to the point where there is pretty much no rigidity. This is due to the significant chain branching that occurs in its polymerisation process, effectively limiting the size of the dispersion forces. Hence LDPE is used for cling wrap. HDPE, however is produced catalytically at an electron arrangement site, which means that it does not experience significant chain branching. This dispersion forces to be much stronger, and hence contributes to its greater rigidity, and hence is commonly used in plastic containers and rubbish bins.

PS also comes in two forms, expanded (aerated) or crystal. Crystal PS is a very highly rigid structure due to the bulky benzene ring constituent, that allows it for it to "lock" within each other. This means it is commonly used in tool handles and drinking glasses (of "fake" glass). However, in aerated PS, as the PS is cooling down from the polymerisation process, an inert gas is blown into it, expanding it. This inert gas gives the PS very low density and also is now a heat insulator due to the gases trapped, and hence is used in eskies packaging form (as it can absorb shocks quite well) and foam cups.

 

[pheelx3]

Where are you getting the two carboxylic acid functional groups from? (then pllss stop this massive derail haha)

What do you mean? I'm looking at the pentane carbon backbone, which has a carboxylic acid attached to both ends.
Oh shit i meant to type "3-carboxy-3-hydroxypropane-1,5-dicarboxylic acid"

The true systematic name doesn't require to name one of the carboxylic acid at carbon 1 (because you always name the carbon compound starting at the carboxylic acid at carbon 1)
So 3-carboxy-3-hydroxypropane-5-dicarboxylic acid

But yeah okay back on topic, I answered the last question.
Shoot me another.

 

[pheelx3]

Discuss the benefits and limitations in modelling chemical compounds, and how the models explains the trends in alkanoic acids, alkanols and alkenes
6 marks, go.

 

[SuchSmallHands]

Discuss the benefits and limitations in modelling chemical compounds, and how the models explains the trends in alkanoic acids, alkanols and alkenes
6 marks, go.

Benefits:
- allows for the visualisation of processes that cannot normally be physically seen
- allows appreciation for the 3-dimensional nature of chemical species

Limitations:
- modelling kits like 'molymod' illustrate electrons as fixed plastic that physically connects vacancies in two atoms, rather than depicting them as being positioned in an unknown exact location in orbitals as part of a cloud about the nucleus, which overlap with orbitals of other species to form covalent bonds and which are transferred from one species to another to form ions. This can confuse students' understanding of what the current model of the atom entails, and oversimplifies the nature of bonding
- atoms are often not represented to scale in 2D depictions or 3D models, as such, understanding of the relative size of atoms involved in a process or molecule may be distorted.

Use in explaining trends
- demonstrates the fact that the alkanoic acid molecule has two points which may be susceptible to hydrogen bonding, while there is only one such point on the alkanol molecule. Thus models can depict why alkanoic acids have higher melting and boiling points due to the stronger intermolecular forces between individual alkanoic acid molecules.
- demonstrates the double bond in alkenes, which is easily broken ('opened up') to leave a single C-C bond, thus illustrating why the boiling point and melting point of alkenes are much lower than those of alkanols and alkanoic acids.

Yeah I'm only talking about boiling point/melting point trends. Cbf doing anything else.

 

[pheelx3]

Benefits:
- allows for the visualisation of processes that cannot normally be physically seen
- allows appreciation for the 3-dimensional nature of chemical species

Limitations:
- modelling kits like 'molymod' illustrate electrons as fixed plastic that physically connects vacancies in two atoms, rather than depicting them as being positioned in an unknown exact location in orbitals as part of a cloud about the nucleus, which overlap with orbitals of other species to form covalent bonds and which are transferred from one species to another to form ions. This can confuse students' understanding of what the current model of the atom entails, and oversimplifies the nature of bonding
- atoms are often not represented to scale in 2D depictions or 3D models, as such, understanding of the relative size of atoms involved in a process or molecule may be distorted.

Use in explaining trends
- demonstrates the fact that the alkanoic acid molecule has two points which may be susceptible to hydrogen bonding, while there is only one such point on the alkanol molecule. Thus models can depict why alkanoic acids have higher melting and boiling points due to the stronger intermolecular forces between individual alkanoic acid molecules.
- demonstrates the double bond in alkenes, which is easily broken ('opened up') to leave a single C-C bond, thus illustrating why the boiling point and melting point of alkenes are much lower than those of alkanols and alkanoic acids.

Yeah I'm only talking about boiling point/melting point trends. Cbf doing anything else.

4-5/6
Marking criteria
1 - Benefits of models
1 - Limitations of models
1 - Melting/Boiling points of alkanoic acids which is the highest due to greatest extent of H-bonding
1 - Melting/Boiling points of alkanols due to H-bonding (albeit to a lower extent than alkanoic acids)
1 - Melting/Boiling points of alkenes only due to dispersion forces
1 - All of the alkenes, alkanols and alkanoic acids increase in series due to greater dispersion forces

Yeah I'm only talking about boiling point/melting point trends. Cbf doing anything else

Shit yeah that's all that I was looking for, my bad, I forgot to say that in the q

demonstrates the double bond in alkenes, which is easily broken ('opened up') to leave a single C-C bond, thus illustrating why the boiling point and melting point of alkenes are much lower than those of alkanols and alkanoic acids.

Don't like this, though.

Even though it is easily reacted with and shit that doesn't necessarily mean that intermolecular bonds are weaker. You're confusing intermolecular and intramolecular bonds (ahem prelim chemistry). Unless you meant that the double bond means less hydrogens but then you haven't explicitly said that.

 

[SuchSmallHands]

4-5/6
Even though it is easily reacted with and shit that doesn't necessarily mean that intermolecular bonds are weaker. You're confusing intermolecular and intramolecular bonds (ahem prelim chemistry). Unless you meant that the double bond means less hydrogens but then you haven't explicitly said that.

Yeah I don't know wtf I was writing in that last dot point. Sub in 'no hydrogen bonding and relatively low molecular weight' instead.

Describe how technology has enabled the transuranic elements to be produced. (4 marks)

 

[faisalabdul16]

I never learnt the lead acid cell? Only dry cell. Am i meant to know both? FML GG HSC

You're supposed to know either the lead acid or dry cell with another one!

Lead acid cell is better, because if you get a question to do with environment, dry cell has nothing, and you're pretty much screwed.

 

[pheelx3]

Yeah I don't know wtf I was writing in that last dot point. Sub in 'no hydrogen bonding and relatively low molecular weight' instead.

Describe how technology has enabled the transuranic elements to be produced. (4 marks)

Transuranic elements are produced in two ways: either in particle accelerators or in neutron reactors. Both of are technologies that have the ability to produce transuranic elements (as no element heavier than uranium exists naturally).

Neutron reactors break down the fissile 235U which liberates neutrons. These neutrons go on to collide with a target neutron of other elements such as uranium-238, instigating a chain reaction forming neptunium, then plutonium by subsequent beta decays. This technology has allowed for transuranic elements to be produced. This process, however can only produce elements with an atomic number up to ~95. Anything higher will not undergo subsequent beta decays, rather it will just emit alpha particles.

*insert equation which i described up there, too noob to use latex*

Particle accelerators come in two (three) forms: linear particle accelerators and cyclotrons (and synchrotrons). Linear particle accelerators accelerate a charge particle by using vacuum tubes which increase in length. Alternating tubes were connected to an AC power source, allowing for the next tube to accelerate the particle towards it, and then once it moved into that tube, the tube behind it would offer electrostatic repulsion. This accelerated particles towards the speed of light, which was required such that electrostatic forces of repulsion (both positive between nuclei) were overcome. Cyclotrons use the same principle, however, powerful electromagnets are used in acceleration.

One example of particle acceleration is the production of Ds from Pb and Ni (insert equation)

Both of these methods, due to technology, has enabled the transuranic elements to be produced.

 

[seventhroot]

I hear seventhroot is pretty hot, but you might have to ask Adrita for permission first.

He even has root in his name, what more could you want?

hnnnnng sevenroots? his name seem like he is very very sex indded thank you

huehuehue

 

[SuchSmallHands]

@Faisal, have you got any more good calcs?

 

[faisalabdul16]

Transuranic elements are produced in two ways: either in particle accelerators or in neutron reactors. Both of are technologies that have the ability to produce transuranic elements (as no element heavier than uranium exists naturally).

Neutron reactors break down the fissile 235U which liberates neutrons. These neutrons go on to collide with a target neutron of other elements such as uranium-238, instigating a chain reaction forming neptunium, then plutonium by subsequent beta decays. This technology has allowed for transuranic elements to be produced. This process, however can only produce elements with an atomic number up to ~95. Anything higher will not undergo subsequent beta decays, rather it will just emit alpha particles.

*insert equation which i described up there, too noob to use latex*

Particle accelerators come in two (three) forms: linear particle accelerators and cyclotrons (and synchrotrons). Linear particle accelerators accelerate a charge particle by using vacuum tubes which increase in length. Alternating tubes were connected to an AC power source, allowing for the next tube to accelerate the particle towards it, and then once it moved into that tube, the tube behind it would offer electrostatic repulsion. This accelerated particles towards the speed of light, which was required such that electrostatic forces of repulsion (both positive between nuclei) were overcome. Cyclotrons use the same principle, however, powerful electromagnets are used in acceleration.

One example of particle acceleration is the production of Ds from Pb and Ni (insert equation)

Both of these methods, due to technology, has enabled the transuranic elements to be produced.

Bold part - You repeated yourself.

Strong physics/10 haha

4/4

 

[faisalabdul16]

@Faisal, have you got any more good calcs?

 

[enigma_1]

This is worse than torturing me about Milf. What does the question say?

 

[enigma_1]

Are you like nocturnal bro? Why aren't you asleep?

 

[faisalabdul16]

This is worse than torturing me about Milf. What does the question say?

HAHAHAHA i thought you went to sleep