Anyone up for a Shipwrecks Marathon? (1 Viewer)

[Shadowless]

Just wondering, if we can just focus on this (as it is my weakest module =S), and how many people actually do this module on these forums.

Question: Explain why graphite rods are used in an electrolytic cell.

 

[teeah]

Replied to your other post too

Graphite rods are used as they are unreactive unlike other substances such as copper, they can complete an electrical circuit and they provide an inert surface enabling electron exchange to occur (they allow electrons to flow) so a chemical reaction occurs.

Question: The work of early scientists has increased our understanding of electron transfer
reactions. Describe the impact of this work on society.

 

[Shadowless]

Galvani:
- first person to generate an electric current by placing two different metals connected at one end into a dissected frog
- misinterpreted the movement in the frog’s muscle as ‘animal electricity’
- inspired others to investigate the production of electricity.

Volta:
- made the first galvanic cell by separating copper and tin plates with cardboard soaked in brine
- was significant as it was the first source of a direct electric current (DC).

Davy:
- built upon Volta’s discovery by decomposing compounds to pure metals (such as Na and K)
- had a large impact upon society as the metals he discovered have become very useful in modern society

Faraday:
- developed the laws of electrolysis
- first law states that we can determine the mass of a substance formed in electrolysis if we know the quantity of electricity used

All of these scientists have had a huge impact on society as their discoveries have led to the standard of living we experience today. Advances in lighting, heating, transport and communication have been largely due to the discovery of electricity and galvanic cells and batteries.

Question: Compare the use and effectiveness in preventing corrosion of different protective coatings on containers.

 

[Shadowless]

Question: Compare the use and effectiveness in preventing corrosion of different protective coatings on containers.

Noone?

 

[madharris]

Question: Compare the use and effectiveness in preventing corrosion of different protective coatings on containers.

I would probably use a table for this:
Physical protection - Placing a barrier between the water and oxygen iron can prevent corrosion e.g. organic paints and polyurethane. However this is hard to maintain due to chemical leaching and physical abrasion
Coating with other metals - This also sets up a physical barrier. e.g. tin plating can also be effective by excluding oxygen and water, however if it's damaged and is eposed to the iron, the iron will rust rapidly due to iron being more reactive than the tin.
Passivating the metal - Alloying steel with passivating metals give it protection. e.g. Nickel alloy steel forms a protective layer of nickel II oxide.
Surface Alloys - CHromium bombard a steel surface at high temperatures, the ions are allowed to bond to the steel to form a harder, more corrosion resistant surface. The steel surface forms a passivating layer as the chromium reacts with oxygen

I'm not that good at shipwrecks, tell me if I missed anything, or if i got anything wrong.

Corrosion is a major problem for vessels that have to operate in a variety of 6 aquatic environments. Analyse how the factors in aquatic environments have impacted on the choice of metals used in the construction of vessels over time.
6 marks

 

[nirukk]

Corrosion is a major problem for vessels that have to operate in a variety of 6 aquatic environments. Analyse how the factors in aquatic environments have impacted on the choice of metals used in the construction of vessels over time.
6 marks

The early ships contained iron as the main metal for most of its counterparts. Due to the fact that aquatic environment are salty, it accelerate the process or rusting. This meant that the iron in ships were rusting overtime and incapable of lasting a long time at the marine environment. By the 1800s, metallurgists found a way of incorporating steel as the main ship building material over Iron. Since pure iron was harder to manufacture, steel had the advantage of being malleable and resistant to corrosion than Iron even though it was susceptible to corrosion. Steel at this time were also known to contain impurities such as phosporous & sulfur which made them brittle at low temperatures at sea. Overtime a range of metals were used. Bronze (Alloy of copper) nails and copper hulls were used due to its low susceptibility to corrosion. Copper was also known to be toxic to Toredo worms which attacks the hull, thus protecting it from any attacks. Lead was also used in the ship building process but it was known to be toxic to the marine life. Eventually, stainless steel (nickel-chromium steel) was used to protect the ship from further corrosion as well as surface alloys which bombard nickel and chromium only on the ship's surface. This have been effective against corrosion at aquatic environment.

I need to explain more about bronze, lead, copper so correct me