HSC 2012-2015 Chemistry Marathon (archive) (4 Viewers)

[HeroicPandas]

re: HSC Chemistry Marathon Archive

c) Sugar cane (extraction) -> Glucose (fermentation) -> Ethanol (distillation) -> Ethylene (read question again)

Question 2:

a)
i) Chloroethene
ii) Poly..ethenylbenzene?
iii) Ethenylbenzene (its ethene)

bold

 

[Dementured]

re: HSC Chemistry Marathon Archive

For outline the steps of the polymerisation of ethylene (3 marks)
Would you have to describe both LDPE and HDPE processes?

 

[superSAIyan2]

re: HSC Chemistry Marathon Archive

(b) Describe FIVE quantitative changes that could be observed during the operation of this cell

1. Mass of lead anode decreases as lead oxidises to Pb2+
2. Mass of copper cathode increases as Cu2+ reduces to Cu solid
3. The conc of lead ions in the anolyte increases
4. The conc of copper ions in the catholyte decreases (i think you can measure this using electrical conductivity)
5. Using a voltmeter with negative terminal connected to the anode, you should get a positive voltage as electrons travel from anode to cathode

 

[khoavo12]

re: HSC Chemistry Marathon Archive

Hi just a quick question: in a titration, which solution do we put in the burette and which in the flask? I read some different sources and they are not the same. Is it the known concentration solution or unknown? Thanks everyone

 

[Dementured]

re: HSC Chemistry Marathon Archive

Hi just a quick question: in a titration, which solution do we put in the burette and which in the flask? I read some different sources and they are not the same. Is it the known concentration solution or unknown? Thanks everyone

Burette: solution of known concentration
Flask: solution of unknown concentration + indicator

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

For outline the steps of the polymerisation of ethylene (3 marks)
Would you have to describe both LDPE and HDPE processes?

um i would describe the general process (IPT - initiation, prop....) then distinguish between LDPE and HDPE by initator molecule, catalyst, and high/low temp&pressure

1. Mass of lead anode decreases as lead oxidises to Pb2+ (yes)
2. Mass of copper cathode increases as Cu2+ reduces to Cu solid (yes)
3. The conc of lead ions in the anolyte increases (yes)
4. The conc of copper ions in the catholyte decreases (i think you can measure this using electrical conductivity) (yes)
5. Using a voltmeter with negative terminal connected to the anode, you should get a positive voltage as electrons travel from anode to cathode yes)

you can also talk about the salt bridge, otherwise, well done

 

[superSAIyan2]

re: HSC Chemistry Marathon Archive

^How would you talk about quantitative changes with the salt bridge?

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

^How would you talk about quantitative changes with the salt bridge?

sorry supersaiyan - u can say nothing about the salt bridge

 

[bedpotato]

re: HSC Chemistry Marathon Archive

How many isomers can exist for C₃H₆Cl₂?

 

[ocatal]

re: HSC Chemistry Marathon Archive

How many isomers can exist for C₂H₆Cl₂?

Shouldn't it be C₃H₆Cl₂?

 

[vilst3r]

re: HSC Chemistry Marathon Archive

concentration of salt bridge decreases as it moves to respective half cells to maintain charge neutrality?

(or does the salt bridge allow for the migration of ions from half cell to half cell? my understanding of salt bridge may be missing some stuff lol)

Yeah that seems about right, the moles of anions and cations from the salt bridge will eventually run out after flowing to their respective cells.

 

[bedpotato]

re: HSC Chemistry Marathon Archive

Shouldn't it be C₃H₆Cl₂?

lol woops. fixed it.

 

[ocatal]

re: HSC Chemistry Marathon Archive

Haha is it 4? Hate these sorts of questions..

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

Yeah that seems about right, the moles of anions and cations from the salt bridge will eventually run out after flowing to their respective cells.

Thank you! BUt can someone else please CONFIRM?

 

[bedpotato]

re: HSC Chemistry Marathon Archive

Haha is it 4? Hate these sorts of questions..

Yep, it is!

Which stateent best describes the equivalence point in a titration between a strong acid and a strong base?
(A) The point at which the first sign of a colour change occurs
(B) The point at which equal moles of acid and base have been added together
(C) The point at which equal moles of H⁺ ions and OH^- ions have been added together
(D) The point at which the rate of the forward reaction equals the rate of the reverse reaaction

 

[Menomaths]

re: HSC Chemistry Marathon Archive

Yep, it is!

Which stateent best describes the equivalence point in a titration between a strong acid and a strong base?
(A) The point at which the first sign of a colour change occurs
(B) The point at which equal moles of acid and base have been added together
(C) The point at which equal moles of H⁺ ions and OH^- ions have been added together
(D) The point at which the rate of the forward reaction equals the rate of the reverse reaaction

b?

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

Yep, it is!

Which stateent best describes the equivalence point in a titration between a strong acid and a strong base?
(A) The point at which the first sign of a colour change occurs
(B) The point at which equal moles of acid and base have been added together
(C) The point at which equal moles of H⁺ ions and OH^- ions have been added together
(D) The point at which the rate of the forward reaction equals the rate of the reverse reaaction

(C)

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

b?

Consider polyprotic acids/bases

 

[Menomaths]

re: HSC Chemistry Marathon Archive

Consider polyprotic acids/bases

Oh yeah true

 

[bedpotato]

re: HSC Chemistry Marathon Archive

b?

Nah, it's C.

2006 HSC, q9.