Chemistry: Checklist (2 Viewers)

[OmmU]

lol that guy
At OP,
I tihnk for shipwrecks you should i also go over the historical developement of the choice of materials used in ships as well, they might ask a few markesr on it given that this years HSC is pretty fked up

Amen to that :\ Preparing for the worst for chem...

 

[Dylanamali]

For Industrial Chem, last time they asked a question on shrinking world resources was 06, reckon we'll see it again this year?

 

[dan2452]

I'm fucked for Chemistry...
about to start "Revise HSC Chemistry Core in a month" in a day

doing that right now, think i'm learning nothing but hoping it sinks in subconsciously =(

 

[1981Grant]

Yeah I have a really bad feeling for chem as well so I'm trying to cover all my bases. I'm hoping for heaps of calculation questions, i'm expecting I'll get asked on the batteries and lots of chemical monitoring and management where I'm weakest.

 

[UnrealAnchovies]

For Industrial Chem, last time they asked a question on shrinking world resources was 06, reckon we'll see it again this year?

yeah i reckon this years question will be on that

the other (a little less likely) option will be industrial production of sodium hydroxide

 

[Coldplay7]

Does anyone know when to use rather than ??

 

[1981Grant]

I'm worried about option as well.

 

[brachester]

how come the carbon content of mild steel and structural steel promote rusting?

 

[asroma15]

For Industrial Chem, last time they asked a question on shrinking world resources was 06, reckon we'll see it again this year?

what would be in the shrinking resources question ?

 

[Barry K]

Does anyone know when to use rather than ??

if they give u the energy (eg. energy released by this thingo is 200kJ), you have to multiply it ('it' being the energy in kJ) by the number of moles of fuel burnt. So (delta)H= energy * moles of fuel burnt. Whatever answer you get is the enthalpy, which is (delta)H. And then you can use the formula (delta)H= -m * C * (delta)T and just replace (delta)H with the answer from above. So basically, Energy released * moles of fuel burnt = -m * C * (delta)T.

I dont really know why you would use the Q equation, i never really used it. The teacher showed us how to use it, but the method i showed u above works just as well.

lol if u read this before u go to the exam, hope this helped!

 

[Barry K]

what would be in the shrinking resources question ?

the question would be like "identify one natural resource (which would be other than fossil fuels obviously) that is shrinking/depleting (or sumthin like that) and identify alternatives to this source." lol thats probably the most badly worded question in the world.. but u get my drift, at least i hope u do..

to that question, you can write about how natural sources of rubber were in high demand before WW2 and that the supply was greater than demand (they needed the rubber for tyres and stuff), so they had to think of different alternatives to satisfy this demand for rubber. so they made synthetic rubbers such as styrene-butadiene (SBT), poly(isoprene) and poly(isobutylene). or you can think of other resources that are/were running out that needed replacing..

Hope this helped

 

[1981Grant]

how come the carbon content of mild steel and structural steel promote rusting?

I'm not sure if I can explain this but I'll give it a shot.

Chromium and Nickel alloys are used in steel as they form an insoluble oxide layer over the steel, this prevents rusting/corrosion from occuring. Carbon is also used in steel to reinforce it, e.g. structural steel, when there is a large percent of carbon in the steel (>2%), the carbon can begin to corrode, this carbon will then allow a site for reduction/oxidation to take place.

Mild steel and structural steel have a larger percentage of carbon in them and no galvanic components.

 

[brachester]

I'm not sure if I can explain this but I'll give it a shot.

Chromium and Nickel alloys are used in steel as they form an insoluble oxide layer over the steel, this prevents rusting/corrosion from occuring. Carbon is also used in steel to reinforce it, e.g. structural steel, when there is a large percent of carbon in the steel (>2%), the carbon can begin to corrode, this carbon will then allow a site for reduction/oxidation to take place.

Mild steel and structural steel have a larger percentage of carbon in them and no galvanic components.

Yeah i know about the effects of the composition of the steel to its properties. But my question is why does carbon promote rusting? You said something about it allow a site for reduction/oxidation to take place, can you explain that part a bit further?

 

[1981Grant]

Yeah i know about the effects of the composition of the steel to its properties. But my question is why does carbon promote rusting? You said something about it allow a site for reduction/oxidation to take place, can you explain that part a bit further?

I'll be back in a bit with the answer.

 

[1981Grant]

Yeah i know about the effects of the composition of the steel to its properties. But my question is why does carbon promote rusting? You said something about it allow a site for reduction/oxidation to take place, can you explain that part a bit further?

I've looked into it and what I can find says it is because the carbon begins to corrode it acts as a cathode and forces iron to be an anode. The fact that the carbon is always being dissolved shifts the equilibrium to favour the reduction of carbon and thus the oxidation of iron.

My source for this is an old success book. I hope this helps.

 

[brachester]

I've looked into it and what I can find says it is because the carbon begins to corrode it acts as a cathode and forces iron to be an anode. The fact that the carbon is always being dissolved shifts the equilibrium to favour the reduction of carbon and thus the oxidation of iron.

My source for this is an old success book. I hope this helps.

Oohh, it actually makes sense. Cheers man, appreciate it

 

[mirakon]

screw you chemistry

 

[1981Grant]

screw you chemistry

agreed. Don't worry though after tomorrow you won't have to do it at school level ever again.

 

[CalumGemmell]

For chem, what raw marks to state rankers normally get?

 

[Georgina168]

For the industrial chem, can we just reiterate glucose and using ethanol and a fuel instead of petroleum?