HSC 2012-2015 Chemistry Marathon (archive) (7 Viewers)

[Riproot]

A bit strange to allocate 3 marks to that question, a comparison and 3 equations is a bit too much - I think.

I disagree.

 

[Magical Kebab]

re: HSC Chemistry Marathon Archive

A bit strange to allocate 3 marks to that question, a comparison and 3 equations is a bit too much - I think.

I got it from a past hsc exam.

 

[Immortalp00n]

re: HSC Chemistry Marathon Archive

Compare the process of polymerisation of ethylene and glucose. Include 3 relevant chemical equations in your answer. (3 marks)

Ethylene:
-Produced by Addition ( a double bond is broken )
n CH2=CH2 ..........> n [ -CH2-CH2- ]

Glucose:
-Produced by condensation (one molecule of water is released and a glucose is added)
n(C6H12O6) --------------> (-C6H12O6-)n +(n-1)H2O ( n-1 as 2 glucose molecules give one molecule of water)

3 chemical equations :S????

 

[Immortalp00n]

re: HSC Chemistry Marathon Archive

Using examples of named polymers, compare and contrast addition polymerisation with condensation polymerisation. Make reference to the sources of reactants and the process used in the manufacture of the reactant.

 

[Aysce]

re: HSC Chemistry Marathon Archive

The structure below shows one example of a polymer classified as a type of nylon.

Draw structural formulae of the monomers which produced the nylon polymer shown above.

Incorrect.

 

[nightweaver066]

re: HSC Chemistry Marathon Archive

Monomers:

NH = (CH2)8 - NH and CO = (CH2)4 - CO

Not entirely sure, I just learnt it today! Though I'm fairly confident kekeke.

Nope, good try though

Perhaps move further in to the HSC chemistry course and then reattempt this question.

 

[Aysce]

re: HSC Chemistry Marathon Archive

Nope, good try though

Perhaps move further in to the HSC chemistry course and then reattempt this question.

I'll solve it tomorrow

I'm assuming this involves condensation polymers?

 

[nightweaver066]

re: HSC Chemistry Marathon Archive

I'll solve it tomorrow

I'm assuming this involves condensation polymers?

Yep

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

The structure below shows one example of a polymer classified as a type of nylon.

Draw structural formulae of the monomers which produced the nylon polymer shown above.

My go:


HO - C - (CH2)4 - C - OH and H - N - (CH3)6 - N - H

on top of each single carbon that is bolded is a double bond and O
on top of each single nitrogen that is bolded is a double bond and an H

 

[nightweaver066]

re: HSC Chemistry Marathon Archive

My go:


HO - C - (CH2)4 - C - OH and H - N - (CH3)6 - N - H

on top of each single carbon that is bolded is a double bond and O
on top of each single nitrogen that is bolded is a double bond and an H

Very close but not quite. Reread what you typed and you'll probably figure it out.

 

[Immortalp00n]

re: HSC Chemistry Marathon Archive

My go:


HO - C - (CH2)4 - C - OH and H - N - (CH3)6 - N - H

on top of each single carbon that is bolded is a double bond and O
on top of each single nitrogen that is bolded is a double bond and an H

.\single brah

 

[nightweaver066]

re: HSC Chemistry Marathon Archive

Explain the different reactivity of butane and 1-butene with aqueous bromine, illustrating your answer with a chemical equation using structural formulas. (2 marks)

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

Very close but not quite. Reread what you typed and you'll probably figure it out.

.\single brah

SO diAMIDE is:

H2N-R-NH2?

 

[someth1ng]

re: HSC Chemistry Marathon Archive

The structure below shows one example of a polymer classified as a type of nylon.

Draw structural formulae of the monomers which produced the nylon polymer shown above.

H2N-(CH2)6-NH2 and COOH-(CH2)4-COOH

The condensation reaction removes the hydrogen from the amine group and the -OH from the carboxyl group - this produces water as the by-product.

I'm not entirely sure but it makes sense to me since it's similar to the condensation reaction between amino acids to make proteins.

 

[Aysce]

re: HSC Chemistry Marathon Archive

H2N-(CH2)6-NH2 and COOH-(CH2)4-COOH

The condensation reaction removes the hydrogen from the amine group and the -OH from the carboxyl group - this produces water as the by-product.

I'm not entirely sure but it makes sense to me since it's similar to the condensation reaction between amino acids to make proteins.

I got this answer as well and it does make sense since you're forming small molecules ie water and you have two functional groups: the amine and carboxylic acid groups.

 

[Aysce]

re: HSC Chemistry Marathon Archive

Explain the different reactivity of butane and 1-butene with aqueous bromine, illustrating your answer with a chemical equation using structural formulas. (2 marks)

Butane has very little to no reactivity with aqueous bromine when mixed together. This is a direct result of the alkane-bromine water mixture not being exposed to any ultra violet light thus preventing drops of added aqueous bromine from being decolourised. Although, the reactivity of 1-butene with bromine water is relatively high in comparison as the alkene does not require the presence of u.v. light to react with bromine water and also because it possesses a double bond which can facilitate the joining of 2 atoms by 'opening up'.

This is evidenced through the addition reaction:

CH3 - CH2 - CH = CH2 + HOBr -----> CH3 - CH2 - CH (connected to the hydroxyl group) - CH2 (connected to Br atom)

I tried

 

[Eg155]

re: HSC Chemistry Marathon Archive



idgi.
someone pls enlighten me as to why it is C?

 

[deswa1]

re: HSC Chemistry Marathon Archive

View attachment 27382

idgi.
someone pls enlighten me as to why it is C?

An isomer is like a re-arrangement of the haloalkane. It can't be A or B because they both have one fluorine but the original has 2 and it can't be D because that's what that haloalkane is called now

 

[Magical Kebab]

re: HSC Chemistry Marathon Archive

An isomer is like a re-arrangement of the haloalkane. It can't be A or B because they both have one fluorine but the original has 2 and it can't be D because that's what that haloalkane is called now

I wudve thought D...

 

[deswa1]

re: HSC Chemistry Marathon Archive

I wudve thought D...

But D is the name of the molecule IN the question- for an isomer, it has to be something else. Watch out for this, they often include the name of the molecule shown as one of the options.