General thoughts: HSC chemistry 2015 (4 Viewers)

[BlueGas]

NaOH conc

Yeah I wrote 0.18

 

[Sarthakgarg]

What did you guys put in for the battery 4-marker. I thought fuel cell is the same as lead-acid cell so I wrote all about it. If it isn't the same, then wouldn't fuel cell be outside the syllabus?

 

[TQuadded]

What did you guys put in for the battery 4-marker. I thought fuel cell is the same as lead-acid cell so I wrote all about it. If it isn't the same, then wouldn't fuel cell be outside the syllabus?

Fuel cell uses oxygen + hydrogen = water to generate a potential difference I think.

 

[Sarthakgarg]

Fuel cell uses oxygen + hydrogen = water to generate a potential difference I think.

But isn't this outside the course?...

 

[TQuadded]

But isn't this outside the course?...

I don't think so. Check the syllabus, I could be wrong. I just remember studying about it.

 

[Sarthakgarg]

I don't think so. Check the syllabus, I could be wrong. I just remember studying about it.

Damn it....just checked it's different. How many marks do you think I'd lose?

 

[TQuadded]

Damn it....just checked it's different. How many marks do you think I'd lose?

All of them most likely. If you're lucky maybe you'll get one. If the cost and practicality are correct though then you should get like half the marks, but then again they're for the wrong cell.

 

[Sarthakgarg]

All of them most likely. If you're lucky maybe you'll get one. If the cost and practicality are correct though then you should get like half the marks, but then again they're for the wrong cell.

But instead of writing "lead-acid cell" in my response, I wrote "fuel cell" throughout even in th cost and practicality part. And I think a fuel cell has the same issues as lead-acid cell. Should I get at least two....for cost and practicality????

 

[TQuadded]

But instead of writing "lead-acid cell" in my response, I wrote "fuel cell" throughout even in th cost and practicality part. And I think a fuel cell has the same issues as lead-acid cell. Should I get at least two....for cost and practicality????

If you wrote about how it's not as practical as the smaller cells and say it's expensive because it needs to be able to hold hydrogen and stuff, + it's flammable, then you might even get three.

 

[synx]

sooo has anyone seen some solutions up yet or nah

 

[Leyfae]

B cause it was a carbon fluorine and hydrogen

 

[nerdz1]

But instead of writing "lead-acid cell" in my response, I wrote "fuel cell" throughout even in th cost and practicality part. And I think a fuel cell has the same issues as lead-acid cell. Should I get at least two....for cost and practicality????

But "lead-acid" wasn't one of the options you were given so even if you used it, likely you would not be awarded the marks.

 

[Torque]

Hey guys. For the question asking to discuss properties of a non-medical radioisotope related to its properties, I did not include any disadvantages. However, I did explain the advantages of 3 properties of Cobalt-60 related to its use in industrial radiography and gave a thorough explanation of how it works. Would I lose many marks here?

Also, for the question asking to describe a safe method for saponification, I think I said to use ethanol (instead of an ethanol-water mixture) as an amphipathic solvent to dissolve the triglyceride fat and ethanol an allow the saponification reaction to occur. Would I lose marks for missing the importance of water in the saponification process because sodium hydroxide has a much higher solubility in water (10 times as much compared to ethanol solvent)?

Thanks

 

[Sarthakgarg]

Hey guys. For the question asking to discuss properties of a non-medical radioisotope related to its properties, I did not include any disadvantages. However, I did explain the advantages of 3 properties of Cobalt-60 related to its use in industrial radiography and gave a thorough explanation of how it works. Would I lose many marks here?

I guess since it's a discuss question...you might lose maybe 2 for the 5 marker, just because I think the question states "discuss it's use in the industry in terms of its properties..." But other than that, you should be fine for that one...

 

[TQuadded]

Hey guys. For the question asking to discuss properties of a non-medical radioisotope related to its properties, I did not include any disadvantages. However, I did explain the advantages of 3 properties of Cobalt-60 related to its use in industrial radiography and gave a thorough explanation of how it works. Would I lose many marks here?

Also, for the question asking to describe a safe method for saponification, I think I said to use ethanol (instead of an ethanol-water mixture) as an amphipathic solvent to dissolve the triglyceride fat and ethanol an allow the saponification reaction to occur. Would I lose marks for missing the importance of water in the saponification process because sodium hydroxide has a much higher solubility in water (10 times as much compared to ethanol solvent)?

Thanks

I used Cobalt-60 as well and gave three industrial uses. I also said that it can't be used medically in a fashion similar to Iodine-131 because of its long half-life, in conjunction with powerful and harmful gamma rays. I concluded that although it can be harmful with gamma rays, it's effective for its industrial uses.

By just giving advantages, I think you limit yourself to about 3 marks. (I believe the question asked to "discuss".)

 

[monopoly73]

Why was that worth 4 marks?

3(0.1)(0.025)/0.0415=0.181 M

maybe because you had to write an equation which would constitute to 1 mark. but to be honest im not really sure

 

[HecticLad]

I used Cobalt-60 as well and gave three industrial uses. I also said that it can't be used medically in a fashion similar to Iodine-131 because of its long half-life, in conjunction with powerful and harmful gamma rays. I concluded that although it can be harmful with gamma rays, it's effective for its industrial uses.

By just giving advantages, I think you limit yourself to about 3 marks. (I believe the question asked to "discuss".)

Discuss is provide point for and/or against, if he provided enough information for it and related its properties to its use well, then he shouldnt lose marks

 

[malcolm21]

maybe because you had to write an equation which would constitute to 1 mark. but to be honest im not really sure

u dont need an equation, you just say its triprotic

 

[malcolm21]

Discuss is provide point for and/or against, if he provided enough information for it and related its properties to its use well, then he shouldnt lose marks

i wrote about strontium 90, and i dont think it has any disadvantages when using it to detect hardness, but i didnt write explicitly it had no disadvantages, do you think ill lose marks?

 

[Torque]

i wrote about strontium 90, and i dont think it has any disadvantages when using it to detect hardness, but i didnt write explicitly it had no disadvantages, do you think ill lose marks?

One disadvantage of Strontium-90 is that it has chemical properties similar to calcium and so can replace calcium in bone, leading to bone cancer and leukemia. Disadvantages you can use for any radioisotope include the high costs to operate nuclear reactors / particle accelerators incurring large costs or ionising radiation leading to cancer / damage to biomolecules and cell membrane / damage to enzyme to catalyse essential biochemical reactions (bad for workers)

I really hope they dont strictly have disadvantages in the marking critieria. I regret not writing this stuff down. Time really was the enemy. I'm in the same boat as you. :/