Answers To Difficult Questions (3 Viewers)

[Forbidden.]

isnt question 6 a

If the answer is Sodium Citrate it does have a pH > 7.
Sodium Hydroxide (Strong Base) + Citric Acid (Weak Acid) --> Sodium Citrate (Basic salt) + Water


The others are wrong.

Sodium Chloride has a pH = 7
Sodium Hydroxide (Strong Base) + Hydrochloric Acid (Strong Acid) --> Sodium Chloride (Neutral salt) + Water

Ammonium Chloride has a pH < 7
Ammonia (Weak Base) + Hydrochloric Acid (Strong Acid) --> Ammonium Chloride (Acidic salt) + Water

Forgot the other one but the weak base ammonia cannot raise the pH to 7 afte neutralisation.

 

[bmwz4]

Well it can't be D because the flame test doesn't have enough energy to excite the atoms to release a wavelength (or does it?)..

question 14 is def D, a is obviously wrong, b can be right but its not quite right, c is wrong because it talks about white light and we know that were using a hollow cathode lamp and this lamp varies between each thing were testing. thus leaving u with D because the light used matches that absorbed or the spectral lines produced in the sample in the falme test. And its the only answer that mentions the flame....u need to flame to convert molecules to atoms....

 

[Forbidden.]

question 14 is def D, a is obviously wrong, b can be right but its not quite right, c is wrong because it talks about white light and we know that were using a hollow cathode lamp and this lamp varies between each thing were testing. thus leaving u with D because the light used matches that absorbed or the spectral lines produced in the sample in the falme test. And its the only answer that mentions the flame....u need to flame to convert molecules to atoms....

A is wrong, AAS is very accurate to 0.1 ppm
B looks tempting.
C is wrong, white light continuous spectrum.
So I saw D as the best option and chose it.

 

[Martyno1]

meh 13/15 is ok as long as i killed the rest *hopefully*

 

[dani06]

I got 18050 or something

HEYY!! just wanna let u no that i got the exact same qs for that answer...hopefully its right, i'm pretty sure it is though

 

[bmwz4]

can sum1 clarify question 9 in mc? ive got 3 wrong from mc

 

[gadbil]

how did everyone work out q10

 

[bmwz4]

meh 13/15 is ok as long as i killed the rest *hopefully*

12/15 for me...fail

 

[Martyno1]

12/15 for me...fail

lol hopefully we still get our 95+ UAI aims

 

[farahodish]

F&%$!!!!!!!!!!!!!!!!!!!

I JUST REALISED!!!!!!!

@#$*&^@# GRRRRR!!!!

you know that multiple choice question bout the Mg and Ca in water?

FFS I PUT HEAVY METAL CONTAMINATION INSTEAD OF HARDNESS!!!!!!!!!!!!

OHMYGOSH HOW STUPID! WHAT THE HELL!?!?!?

like I wouldnt complain if it was just the one..
but i think (after reading all your comments) I didnt get ANY of the calculations right
and I lost a few more marks in the m/c.

there goes my hsc *salutes*

 

[Forbidden.]

how did everyone work out q10

c₁ V₁ = c₂ V₂

(NOTE: You need pH 2 for c₂, to convert:
pH 2 = 10^-2 = 0.01)

0.1 mol L^-1 x 0.09 L = 0.01 x V₂
V₂ = 0.1 mol L^-1 x 0.09 L / 0.01 mol L^-1
V₂ = 0.9 L
V₂ = 900 mL

I don't know if I'm right ... or it should be 900 mL - 90 mL = 810 mL

 

[jordanst]

Anyone know the answers to question 12 and 13.

I think i only got 12/15 GRR

 

[joshuajspence]

Anyone know the answers to question 12 and 13.

I think i only got 12/15 GRR

12A
13A

 

[jordanst]

Thanks, I put a for 12 but d for 13

 

[Forbidden.]

Shit I'm going to get a Band 4 at this rate.

12A
13A

Q12)
You could form carbon soot, carbon monoxide or carbon dioxide depending on xygen levels but water seems to be always formed.

Q13)
Decreasing the pressure favours the reverse reaction which is endothermic and heat will be absorbed rather than be released.

Thanks, I put a for 12 but d for 13

It can't be D, the reverse reaction rate will actually increase due to the decrease in pressure.

 

[~shinigami~]

I got 18050 or something

Same here.


Does anyone remember what the question about Sulfur Dioxide calculation was about?

I think I was being stupid and just skimmed over the question so what I did was calculate the volume and got some massive number 500 something litres. Someone told me the question asked about ppm or something.

 

[k4t5UM0t0]

I wrote free chlorine radical as an initiator because catalysts don't participate in reactions.
For the calculations:
Sulfur dioxide i got somewhere around 2.4L
Chlorine i put down 1.81 x 10^(4) (3s.f)
KOH i put down 6 ml

Did anyone else forget to name and draw structural formula for water

 

[roadkiller]

hey guys, just confirming for u, 14 was NOT B as i thought, that answer actually relates to Atomic Emission Spectroscopy, not AAS - so i must conceed that it is D

ppm calculations - i got 18050 ppm chloride, but thought that was too much, so i wrote 180 ppm, but my working was correct - so 1/2marks??
The So2 q - i got 232mL i think - not good for me when i look at ur answers :mad1:

 

[joshuajspence]

I wrote free chlorine radical as an initiator because catalysts don't participate in reactions.
For the calculations:
Sulfur dioxide i got somewhere around 2.4L
Chlorine i put down 1.81 x 10^(4) (3s.f)
KOH i put down 6 ml

Did anyone else forget to name and draw structural formula for water

i got 18000 ppm for the chlorine (to 2 or 3 sig fig i cant remember)

KOH i got 3mL....

 

[Forbidden.]

hey guys, just confirming for u, 14 was NOT B as i thought, that answer actually relates to Atomic Emission Spectroscopy, not AAS - so i must conceed that it is D

ppm calculations - i got 18050 ppm chloride, but thought that was too much, so i wrote 180 ppm, but my working was correct - so 1/2marks??
The So2 q - i got 232mL i think - not good for me when i look at ur answers :mad1:

There is no half-mark in the HSC.
Only 1, 2, 3 and so on ... whole numbers only.