Chemistry paper & Option (1 Viewer)

martin96

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How did people find the chem paper? Honestly, I found it good. Then when I checked multiple choice, I realised I made various silly mistakes. I think I'm going to lose about 9 marks in the core, and about 4 marks in the option. By the way, how do you identify the products of electrolysis of NaCl? (Industrial) I wrote about indicators for OH- ions, and I think the same for hydrogen. Don't know what I wrote for chlorine though.
 

RealiseNothing

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OH- use indicator
hydrogen gas use pop test
chlorine gas bleaches litmus paper

this is what I did
 

bedpotato

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I'm thinking the exact opposite haha. I wrote OH- and I'm scared that they wanted NaOH.
Oh haha
The full equation is 2NaCl + 2H2O --> Cl2 + H2 + 2NaOH
So I thought the three products were Cl2, H2 and NaOH.
I have no idea

Edit: I might be wrong lol
Maybe they'll accept both? But considering it's chemistry marking...
 

pHyRe

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i wrote oxygen as a product, is that wrong?

also, to test for chlorine i said bubble it through a solution of Pb(NO3)2 and see if a white ppt forms. right or wrong?
 

bedpotato

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i wrote oxygen as a product, is that wrong?

also, to test for chlorine i said bubble it through a solution of Pb(NO3)2 and see if a white ppt forms. right or wrong?
No, I thnk it's right. In a past HSC paper, the answers said " H2 or O2" .
 

ocatal

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i wrote oxygen as a product, is that wrong?

also, to test for chlorine i said bubble it through a solution of Pb(NO3)2 and see if a white ppt forms. right or wrong?
Oxygen is correct but it asked for only one aqueous solution of NaCl. So you couldn't have chlorine gas, hydrogen gas and oxygen gas as the products of the electrolysis of only one type of solution. I wrote oxygen as well -.-
 

Menomaths

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Oxygen is correct but it asked for only one aqueous solution of NaCl. So you couldn't have chlorine gas, hydrogen gas and oxygen gas as the products of the electrolysis of only one type of solution. I wrote oxygen as well -.-
I wrote something worse....
 

bedpotato

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Oxygen is correct but it asked for only one aqueous solution of NaCl. So you couldn't have chlorine gas, hydrogen gas and oxygen gas as the products of the electrolysis of only one type of solution. I wrote oxygen as well -.-
Did you write H2, Cl2 and O2?

What you could've written as the products:
1. O2 OR H2
2. Cl2
3. NaOH
 

AnimeX

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do u guys remember what the flame test question was asking?
 

bedpotato

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do u guys remember what the flame test question was asking?
lol. :p

I'm assuming you're talking about the Ba, Pb, Cu question,

Firstly, it (part c) didn't specifically ask for the flame test. Just a test. You could've used precipitation if you wanted.

Secondly, it was something along the lines of "Describe (or identify) a test that can be used to confirm the identity of the remaining ion". Which was Cu2+.
 

RealiseNothing

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Oh haha
The full equation is 2NaCl + 2H2O --> Cl2 + H2 + 2NaOH
So I thought the three products were Cl2, H2 and NaOH.
I have no idea

Edit: I might be wrong lol
Maybe they'll accept both? But considering it's chemistry marking...
The overall equation is NaCl + H2O ---> Cl2 + H2 + Na + OH I think?

Honestly, ~chemistry~
 

RealiseNothing

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Yer I have no idea. Different sources are saying different things. I get the feeling they are looking for NaOH rather than OH- though :(
 

Menomaths

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Yer I have no idea. Different sources are saying different things. I get the feeling they are looking for NaOH rather than OH- though :(
Pretty sure OH- is okay?

Also, NaOH is used as a cleaning agent so do you think my answer would be good?
 

AnimeX

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lol. :p

I'm assuming you're talking about the Ba, Pb, Cu question,

Firstly, it (part c) didn't specifically ask for the flame test. Just a test. You could've used precipitation if you wanted.

Secondly, it was something along the lines of "Describe (or identify) a test that can be used to confirm the identity of the remaining ion". Which was Cu2+.
I'm not sure why, but me along with a couple of people read it as confirm the identity of the precipitate in part a/b ... so we did barium...
That would be a few lost marks then :(, got flame test bit of it though
 

BlugyBlug

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Oh haha
The full equation is 2NaCl + 2H2O --> Cl2 + H2 + 2NaOH
So I thought the three products were Cl2, H2 and NaOH.
I have no idea

Edit: I might be wrong lol
Maybe they'll accept both? But considering it's chemistry marking...
Wouldn't it depend on whether it was dilute or concentrated?
 

bedpotato

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why can't you have O2 and H2? electrolysis of water no?
But to produce NaOH, electrolysis of brine occurs, not water? Cl- is oxidised and water is reduced.

Pretty sure OH- is okay?

Also, NaOH is used as a cleaning agent so do you think my answer would be good?
OH- seems okay to me as well, but who knows what's up with the marking criteria.

Was there a question asking for the uses of NaOH? Great. Lol.
 

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