The 2004 HSC - Chemistry Paper (1 Viewer)

[kow_dude]

for that hcl qs

this is how i did it and got ph of 5

n=0.01 x 0.01
=0.0001

and then it was diluted to 100ml, so dilute factor of 10

so u divide 0.0001 by 10 and get 0.00001

so ph=-log[H+]

so =-log 0.00001

=5

but so many people sayings its 3

i got ph = 2.9

 

[chelseafan]

dafidav:

pH= -log[H+]...this means it is the log of hydrogen ion concentration not number of moles of hydrogen ions in solution

As original hydrogen ion cncentration is 0.01mol/L the number of moles present is irrelevant it is just the concentration that counts.

A dilution by factor of ten results in a [H+] of 0.001mol/L

pH= -log[0.001]
= 3

 

[tennille]

wouldnt it be three. its a 1:9 ratio. so its a fraction of 1/10. 1/10 x 0.01 = 0.001. Then -log (0.001) = 3

 

[Plebeian]

I'm pretty sure the HCl had a pH of 3.
-

for that idustrial isotope

can u use technetium 99m??

cos like thats the medical industry

i wasnt sure if you could use medical industry

I don't think so, the syllabus specifies "medicine" and "industry" as two different things, but that doesn't mean you'll get no marks.
-
It's not that surprising that there were no questions about the Haber process, it was there last year for 7 marks.
-
Overall I thought it was a pretty good paper, fairly challenging but nothing too weird.

 

[withoutaface]

i got ph = 2.9

pH was three, because the amount of water was going from 10mL to 100mL, hence a tenfold decrease in H+ conc, hence a +1 increase of pH

 

[dafidav]

dafidav:

pH= -log[H+]...this means it is the log of hydrogen ion concentration not number of moles of hydrogen ions in solution

As original hydrogen ion cncentration is 0.01mol/L the number of moles present is irrelevant it is just the concentration that counts.

A dilution by factor of ten results in a [H+] of 0.001mol/L

pH= -log[0.001]
= 3

ohhhhhhhhhh

right................

damn, thanx for clearing that up

oh well

there goes 2mark or so

 

[rumour]

This was a long test, most of our class left early in the trials & I thought I would leave early in this exam, but it was too long!!!

 

[imperfek_anjel]

i thought id like to say, chem is gay, stupid exam was hard.... =/

p.s. wot did pplz get for the amount of woteva solid it was needed to make the 250mL of standard solution???



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^iMPerFek AnJeL^

 

[golferjim]

what did people get for the concentration of sodium hydrogen carbonate

i got 0.03

 

[TJ297]

Yesssssss

Yess i got that ph of 3 one correct!!!

That brings me up to 6% overall, JKS

 

[tennille]

i got 2.52 grams for the standard solution thing.

 

[ay_caramba]

i thought id like to say, chem is gay, stupid exam was hard.... =/

p.s. wot did pplz get for the amount of woteva solid it was needed to make the 250mL of standard solution???



_________________________________


^iMPerFek AnJeL^

i got 2.something grams.. cant remember, too lazy to calculate it again

 

[Gesus]

yep, 0.0257 or something like that

 

[TJ297]

i thought id like to say, chem is gay, stupid exam was hard.... =/

p.s. wot did pplz get for the amount of woteva solid it was needed to make the 250mL of standard solution???



_________________________________


^iMPerFek AnJeL^

I put 30 grams, but i didnt have a clue... lol ive failed big time...

 

[golferjim]

I think i got 2.52 as well

 

[Tommy_Lamp]

I thought the test was ok, harder than previous years but good. I agree though, alot of extended responses.

 

[imperfek_anjel]

woo hoo mee too!! yay, me who never understands the stupid calculations got that question rite, YAY!

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^iMPerFeK AnJeL^

 

[yulia]

I FINISHED THE EXAM IN AN HOUR. How to fail chemistry in 4 easy steps
1/ Don't turn up to class, with the idea that chemistry won't count for your UAI.
2/ When you realise that chemistry IS counting for your UAI, decide it's too late and not bother anyways.
3/ Don't go near the chapter in your text book on your option topic.
4/ Finish the entire paper in under an hour.
And that sums up my chemistry mark. Oh well.

 

[Narelle]

That was the maddest test...

big markers were like englishy bullcrap

not that much specific questions, really open ended

shipwrecks questions rocked too

 

[Bridget]

Yay, i got ph3.
The first question in the short responses was crap, sodium hydrogen carbonate.... NO idea!

Generally I thought that was a good paper. Some memory questions which I had trouble with (testing methods for anions, look for precipitates etc) but I thought BOS was very nice to us.