Predictions for Chemistry 2014 HSC? (10 Viewers)

[enigma_1]

2013 chemistry HSc MC,

A )

 

[QZP]

Lead acid cell.

Lead.

Acid.

I never learnt the lead acid cell? Only dry cell. Am i meant to know both? FML GG HSC

 

[pheelx3]

I never learnt the lead acid cell? Only dry cell. Am i meant to know both? FML GG HSC

nope you only are required to know one.
but some questions are better focused with one or the other.
I learnt both because I'm a nerd like that.

 

[nerdasdasd]

Explain how microscopic membrane filters purify contaminated waters, in terms of their design and competition. (4 marks)

 

[QZP]

Yes but you said one benefit, and I didn't feel like talking about environmental benefit so i decided to go with social impacts...
Its not wrong :C but that's because im lazy and its a 2 marker. If it was a 3-4 or more marker, then yeah no shit talk about the lead and the acid. I don't think 2 marks calls for that though



A
you know... I always wondered why it isn't
3-hydroxypentane-1,3,5-tricarboxylic acid...

It's a rule in naming molecules to have the least possible sum of numbers

 

[SuchSmallHands]

Yes but you said one benefit, and I didn't feel like talking about environmental benefit so i decided to go with social impacts...
Its not wrong :C but that's because im lazy and its a 2 marker. If it was a 3-4 or more marker, then yeah no shit talk about the lead and the acid. I don't think 2 marks calls for that though

Better responses clearly linked the benefit to a property of lead or sulfuric acid. Weaker responses did not give a specific benefit, but rather general statements that could have many meanings, such as ‘convenient and reliable’. (notes from the marking centre). I don't think your answer would have got 2 based off of that.

 

[QZP]

Honestly, should I learn lead acid cell right now? Where did you get that Q SSH

 

[SuchSmallHands]

I never learnt the lead acid cell? Only dry cell. Am i meant to know both? FML GG HSC

They target lead acid a fair bit, like that environmental impact of a named electrochemical cell would have been a lot easier for lead-acid as well. It's not really fair when the syllabus specifies we only need to know one. My teacher told us we should know a bit on both, and one in depth.

 

[SuchSmallHands]

Honestly, should I learn lead acid cell right now? Where did you get that Q SSH

HSC 2007, all you need to know is that the lead acid cell contains lead and acid.

 

[timeflies]

Honestly, should I learn lead acid cell right now? Where did you get that Q SSH

I don't think you would need to, I did the dry cell as well but did fine in this question when I saw it before because they give a labelled diagram of the cell with Lead and Sulfuric Acid shown so you can infer it.

Edit: The dotpoint only requires you to know one and it'd be really harsh for them to ask a question like this without providing information about the cell so I don't think they'd do it.

 

[SuchSmallHands]

Y
A
you know... I always wondered why it isn't
3-hydroxypentane-1,3,5-tricarboxylic acid...

Shit. Mind blown. Can someone explain this?

 

[pheelx3]

Explain how microscopic membrane filters purify contaminated waters, in terms of their design and competition. (4 marks)

question was one a few pages back. I answered it :L

It's a rule in naming molecules to have the least possible sum of numbers

Yes but, you start on the carbon that is attached to the carboxylic acid as carbon 1. not the next carbon... it's weird.
I've asked a few people and they always just said "oh its a convention"

Better responses clearly linked the benefit to a property of lead or sulfuric acid. Weaker responses did not give a specific benefit, but rather general statements that could have many meanings, such as ‘convenient and reliable’. (notes from the marking centre). I don't think your answer would have got 2 based off of that.

Hmm... I did mention replacing (or lack of). But cheers, thank you, I'll keep that in mind.

Honestly, should I learn lead acid cell right now? Where did you get that Q SSH

Yeah after having learnt both, the lead-acid cell is the better one to be quite honest.
2007.

 

[enigma_1]

Shit. Mind blown. Can someone explain this?

nah just rote learn it. You'll never be asked to justify this

 

[SuchSmallHands]

Yes but, you start on the carbon that is attached to the carboxylic acid as carbon 1. not the next carbon... it's weird.
I've asked a few people and they always just said "oh its a convention"

It's weird because the c is part of the functional group, making it part of the main chain would make the name of the compound weird. I can't believe this hasn't occurred to me before.

Edit: the alternate name you provided would also be wrong pheelx

 

[QZP]

@pheelx3 ooo okay im curious now got me

 

[pheelx3]

It's weird because the c is part of the functional group, making it part of the main chain would make the name of the compound weird. I can't believe this hasn't occurred to me before.

hahaha, yeah I was like dafaq when I learnt it because i was like nigga that carbon backbone has 5 carbons, not 3...

nah just rote learn it. You'll never be asked to justify this

Yeah but still it's just interesting to note that. Lol.
The justification is that it's a convention, apparently
IUPAC just so happened to name it that.

 

[pheelx3]

It's weird because the c is part of the functional group, making it part of the main chain would make the name of the compound weird. I can't believe this hasn't occurred to me before.

Edit: the alternate name you provided would also be wrong pheelx

Hmmm...

3-carboxy-3-hydroxypentanedioic acid?

 

[SuchSmallHands]

Hmmm...

3-carboxy-3-hydroxypentanedioic acid?

It would be something weird, you wouldn't be able to say that there are three carboxylic acid functional groups attached though, because the carbon is part of the main chain now.

 

[zhertec]

I hear seventhroot is pretty hot, but you might have to ask Adrita for permission first.

 

[SuchSmallHands]

I hear seventhroot is pretty hot, but you might have to ask Adrita for permission first.

He even has root in his name, what more could you want?