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Shipwrecks (1 Viewer)

SkimDawg

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How did you guys go in this option?

I thought it was pretty straightforward, except the 7 marker, if you didn't study an australian wreck well, yeah it would have been gay.
 

fishbulb

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Yeh i think i nailed this section.

I did Vernon anchors and HMB Endeavour Cannons. Drew diagrams of electrolysis to go with it.
 

Zephyrio

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My answers: short version

a) i) The rod can be Zinc - anode - oxidised in preference to the steel; steel is reduced and hence it is protected from corrosion.
ii) Two methods: coating the steel with paints such as Rustmaster; coating the steel with zinc (galvanising).

b) i) Comparing the rate of corrosion of an iron and a steel: just weigh both nails, submerge in water (or half submerge) and then observe the results/reweigh the nails.
ii) Iron corrodes more than stainless steel, which is corrosion resistant.
iii) Steel composition may be altered with the introduction of passivating metals such as Cr to increase corrosion resistance.

c) i) Just drew a normal electrolytic cell with AgNO3 instead of water. Cathode electrode coated with silver.
ii) Cathode: Ag+ + e --> Ag(s)
Anode: 2H2O --> 4H+ + O2 + 4e
iii) Four factors that affect the deposition of silver:
- distance between electrodes
- temperature of the apparatus
- concentration of electrolyte
- voltage applied to the system

d) I used the Batavia and the Endeavour Cannons:
Preliminary wash: Hosed down in the case of Batavia; the concretions of the Endeavour were chipped away.
Desalination: Both placed in a NaOH bath; then electrolysed. Drew an electrolytic cell here.
Both impregnated with PEG.
Display: Batavia was considered more fragile so it's in a glass display, whereas the Endeavour was more stable so it's displayed in controlled conditions, low light, low humidity. (Only minor point was made here since the question wanted more on chemical reactions.)

Any disagreements? Lol
 

fishbulb

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Zephyrio said:
My answers: short version

a) i) The rod can be Zinc - anode - oxidised in preference to the steel; steel is reduced and hence it is protected from corrosion.
ii) Two methods: coating the steel with paints such as Rustmaster; coating the steel with zinc (galvanising).

b) i) Comparing the rate of corrosion of an iron and a steel: just weigh both nails, submerge in water (or half submerge) and then observe the results/reweigh the nails.
ii) Iron corrodes more than stainless steel, which is corrosion resistant.
iii) Steel composition may be altered with the introduction of passivating metals such as Cr to increase corrosion resistance.

c) i) Just drew a normal electrolytic cell with AgNO3 instead of water. Cathode electrode coated with silver.
ii) Cathode: Ag+ + e --> Ag(s)
Anode: 2H2O --> 4H+ + O2 + 4e
iii) Four factors that affect the deposition of silver:
- distance between electrodes
- temperature of the apparatus
- concentration of electrolyte
- voltage applied to the system

d) I used the Batavia and the Endeavour Cannons:
Preliminary wash: Hosed down in the case of Batavia; the concretions of the Endeavour were chipped away.
Desalination: Both placed in a NaOH bath; then electrolysed. Drew an electrolytic cell here.
Both impregnated with PEG.
Display: Batavia was considered more fragile so it's in a glass display, whereas the Endeavour was more stable so it's displayed in controlled conditions, low light, low humidity. (Only minor point was made here since the question wanted more on chemical reactions.)

Any disagreements? Lol
I said surface alloys such as stainless steel and applied current methods for a)

I said Iron nail and mild steel nail in 2 different petri dishes with 10ml of water and then record observations throughout 7 days. Keep all the dishes in the same place.

For c)ii) Since there is going to be Ag reduced which requires 0.8v, then it must also have this reduction equation as well:
o2 + h2o + 2e- --> 2OH- (0.4v)
 

SkimDawg

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Looks like I got mostly what you guys got. Except for the steel pipe, for some strange reason I couldnt think of any ways of protecting it other than sac. anodes and electrolysis. sighs.. o well.
 

SkimDawg

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How easy was the prac part? omg, I think I did galv steel as the other nail.
 

vds700

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I thought it was very easy, not sure about my factors affecting rate of electroysis, but apart from that it was good.

My school had been on the maritime museum excursion, which was really helpful for the 7 marker coz id actually seen the artefacts (vernon anchors and endeavour cannon) and they gave us really good notes too, so i think i nailed that 1.
 
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i just talked about very general stuff in the 7 marker cos i did NOT know any specific wreckcs AT ALL...!!

abut i think i did well on the rest of shipwrecks :)
 

Artemis.

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Really liked the 7 marker as I'd studied that a lot, the rest of it was pretty straightforward except for 6 marks on electrolysis stuff, mainly cos I suck at electrolysis.
 

bradman

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Nailed the 7 marker. I thought it was much easier than shipwrecks in past papers
 
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we never did the maritime project. i still said endeavour cannon and vernon anchor but just made techniques for cleaning and restoration up. ah well .
 
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umm cant remember all of em, use of heat, electrolysis, hammers to remove encrustations, desalinise in water....cant remember
 

bradman

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You'll probably still get a few marks. Maybe more than a few? Depends on how pedantic they are about the specific techniques used for both
 

sarah94

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i got confused and wrote about the motor affect
the hsc is really getting me lol
:cold:
 

iEdd

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I'm surprised "Mrs Pooviah" didn't tell YOU the answer was the motor effect, with no logic or reasoning whatsoever, just that as a blunt answer. :rolleyes:
 

Muchi

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u guys since water is lower in series than series isnt it reduced and silveris oxidised? am i confused?
 

bradman

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Silver had to be reduced because it was deposited on one of the electrodes, and I'm pretty sure oxidation of water is higher.
 

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