• Help the next generation of students in the community for the new syllabus!
    Share your notes and exam papers on our Notes & Resources page
  • Like us on facebook here

Section I: Short Answers (1 Viewer)

f(sex)

New Member
Joined
Nov 15, 2007
Messages
29
Location
Westmead
Gender
Male
HSC
2008
danz90 said:
We'll i'd imagine that the salt bridge wouldn't allow that.
... the salt bridge's function is to allow the movement of charges
 

Kearnzo

Member
Joined
Sep 4, 2007
Messages
48
Gender
Male
HSC
2008
f(sex) said:
... the salt bridge's function is to allow the movement of charges
True.. but which ions?

Hm, yeh the catchment was a bit different.

I forgot completly what a buffer in nature was. So i said "assuming acetic acid is a buffer in nature".

What did everyone get for the basic, acidic, neutral salts??

Also what equation did you use for one of the basic or acidic salts?
 

f(sex)

New Member
Joined
Nov 15, 2007
Messages
29
Location
Westmead
Gender
Male
HSC
2008
Kearnzo said:
True.. but which ions?

Hm, yeh the catchment was a bit different.

I forgot completly what a buffer in nature was. So i said "assuming acetic acid is a buffer in nature".

What did everyone get for the basic, acidic, neutral salts??

Also what equation did you use for one of the basic or acidic salts?
cations and anions of course
by that we mean all ions including chloride and nickel ions

and the ammonium salts were acidic, sodium chloride was neutral and the acetate was basic

also buffers in nature included blood and natural water ways, and to the best of my knowledge the acetate/acetic acid buffer isnt very common, but its not wrong
 

Kearnzo

Member
Joined
Sep 4, 2007
Messages
48
Gender
Male
HSC
2008
f(sex) said:
cations and anions of course
by that we mean all ions including chloride and nickel ions

also buffers in nature included blood and natural water ways, and to the best of my knowledge the acetate/acetic acid buffer isnt very common, but its not wrong
Never really read anything that said some didn't cross over. I was vague in my answer by not specifying which beaker, so hopefully...

Yeh, I knew they occured there, just never learnt what chemicals took part in those buffers.

I guessed it was CH3COO- + H2O --> CH3COOH + OH- ??

And ammonium? NH4 + H2O --> NH3 + H3O+ ?
 

Darrow

Executant of Life
Joined
Mar 16, 2007
Messages
112
Gender
Male
HSC
2008
The electron flow of the galvanic cell was from Nickle to Cl- (the platinum acts as a catalyst for the reaction)
So, wouldnt Cl gas form?
 

Kearnzo

Member
Joined
Sep 4, 2007
Messages
48
Gender
Male
HSC
2008
Darrow said:
The electron flow of the galvanic cell was from Nickle to Cl- (the platinum acts as a catalyst for the reaction)
So, wouldnt Cl gas form?
Possibly, I think if you look at your potentials sheet chlorine gas is more easily reduced than aqueous chlorine.

Also, why would they put the chlorine gas there? They don't usually try and trick people in such a way.
 

Harkaraj

Member
Joined
Apr 8, 2006
Messages
117
Location
Sydney
Gender
Male
HSC
2008
Uni Grad
2013
For the galvanic cell both beakers had to turn green as due to the cathode reaction the Right hand beaker developed a negative charge so the silver ions from the silver nitrate solution migrated via the salt bridge to enable electrical neutrality?!?
 

friction

Member
Joined
May 8, 2006
Messages
494
Gender
Male
HSC
2008
danz90 said:
I got 0.16mg of Zinc.

Once you drew your graph with a line of best fit, you used the average absorbance, and then saw that 1.6mg/L was the average concentration.

then, since the sample was 100mL in volume, you multiply the concentration by volume, to get the mass.

1.6mg/L x 0.100L = 0.16mg
Froth i got that.
 

wLym

Member
Joined
Jun 20, 2007
Messages
217
Gender
Male
HSC
2008
danz90 said:
I got 0.16mg of Zinc.

Once you drew your graph with a line of best fit, you used the average absorbance, and then saw that 1.6mg/L was the average concentration.

then, since the sample was 100mL in volume, you multiply the concentration by volume, to get the mass.

1.6mg/L x 0.100L = 0.16mg
i sat there the whole exam and left that question just sitting there cause it just looked too scary. Then i actually read the question properly in the last 2 minutes and im like easy omg so easy so i got it in the last minute literally then pens down im like fuck im so pleased :) But then when i got outta the exam im like oh man i screwed so much stuff up besides that xD
 

rajeenth

New Member
Joined
Apr 30, 2007
Messages
25
Gender
Male
HSC
2008
for the zinc q isnt 4 tablets 0.16mg/L. so 1 should be 0.04mg/L
 

tasmina

New Member
Joined
Mar 30, 2006
Messages
13
Gender
Female
HSC
2008
the platinum isnt the cathode since its just a medium that accepts the electrons as the chlorine gas can't do that
reduction: Cl2 + 2e- --> 2Cl-
its just like the standard hydrogen half cell potential
prob in thicket i remember reading about it the night before the exam..
 

danz90

Active Member
Joined
Feb 2, 2007
Messages
1,474
Location
Sydney
Gender
Male
HSC
2008
tasmina said:
the platinum isnt the cathode since its just a medium that accepts the electrons as the chlorine gas can't do that
reduction: Cl2 + 2e- --> 2Cl-
its just like the standard hydrogen half cell potential
prob in thicket i remember reading about it the night before the exam..
By definition, that's wat an electrode is - a site where electrons are accepted. You guys surely learnt about inert electrodes...
 

friction

Member
Joined
May 8, 2006
Messages
494
Gender
Male
HSC
2008
rajeenth said:
for the zinc q isnt 4 tablets 0.16mg/L. so 1 should be 0.04mg/L
Nope mate that was already the average. No need to devide by 4.
 

danz90

Active Member
Joined
Feb 2, 2007
Messages
1,474
Location
Sydney
Gender
Male
HSC
2008
Hey, friction...

Now I realised why I screwed up the titration question with HCl...

Originally, when the primary standard solution was made... that was in 250mL right??

Then STUPID STUPID me forgot to divide number of moles of Sodium carbonate by 10, since only 25.00mL aliquots were used, thats why I got 10 times the actual number..
FUCK!

You reckon they'll only take one mark off for that?

So it should've been 0.1057 right?
 

Muchi

Member
Joined
Aug 1, 2006
Messages
113
Gender
Female
HSC
2008
umm so what was the voltage. i got like 0.16 or something but i think i got it wrong as i 4gt that its inert! idiot me!
 

adnan91

Member
Joined
Mar 29, 2008
Messages
351
Location
Disney Land
Gender
Male
HSC
2008
U know for the AAS graph question. For the average mass of zinc tablet. I read 1.7 mg/L off the graph not 1.6 mg/L like most ppl. You think they'll take a mark for that. Im sure they'll accept that?
 
Joined
Feb 6, 2007
Messages
641
Location
Terrigal
Gender
Male
HSC
2008
adnan91 said:
U know for the AAS graph question. For the average mass of zinc tablet. I read 1.7 mg/L off the graph not 1.6 mg/L like most ppl. You think they'll take a mark for that. Im sure they'll accept that?
yeah you would expect so
might lose a mark off your graph though if it isn't accurate??
 

Muchi

Member
Joined
Aug 1, 2006
Messages
113
Gender
Female
HSC
2008
my mate got 0.24 volts and she claims shes right for the galvanic cell. what were the voltages you guys got?
 

Aaron.Judd

Member
Joined
Aug 20, 2008
Messages
372
Gender
Male
HSC
2008
1.6 I think or something like that. Fairly sure its right. I think Mrs Pooviah agreed when we went throguh the paper.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top