how was it (2 Viewers)

[annabackwards]

yes i said pH adjustment is first because the text book said so! as it increases precipitation

Yeah, but what if the water was acidic. Is adding lime really "adjusting the pH"?

Gah stupid textbooks and excel... mine said pH just before flouridation but after settling/sedimentation. I sure BoS agrees with me.

EDIT: Excel said for Australia, CSIRO developed a method whereby pH is adjusted (just before chlorination) in order to allow Magnetite to absorb most of the organic matter in the sewage which is then made to clump etc etc. I am going to believe therefore, the answer is still D.

 

[jono2112]

HSC Online and Excel say the order is: flocculation, sedimentation, filtration, sanitisation, pH adjustment.

BUT the conquering chem says pH is before flocculationa and sedimentation.

I think it is a question which will come under some scrutiny at the marking centre. It just depends on what source they choose to use when marking the answer.

 

[sam5]

concentrated weak acid

so it is a weak acid? I said it is a weak acid, but i said that it was less concentrated than acid 1 (im prolly wrong lol)

 

[4theHSC]

Yeah, but what if the water was acidic. Is adding lime really "adjusting the pH"?

Gah stupid textbooks... mine said pH just before flouridation. I sure BoS agrees with me.

lol dude I'm agreeing with you?

 

[annabackwards]

lol dude I'm agreeing with you?

I thought you said pH is before sedimentation lolol. My apologies XD

 

[amrit92]

that chem paper was weirdass? They skipped so much! Not a single question on Haber Process (cummon!) or nuclear or ozone in the written section... I was really relieved tho about the option Industrial Chem they skipped NaOH topic which i hated so i was stoked! Anyone get 800 for their K value btw? I forgot how 2 draw Glycerol grr...

Galvanic cell WAS really weird whats with that crap? I did Lead as anode, Pt as cathode.. voltage of 0.9V.. suitable electrolyte as KNO3? The questoin tha shocked me was the 6 mark about production of PET bottle and some other ones u could chose... i was like WTF is that??! NEVER LEARNT THAT about the physical processes.. i just talked about addition P and then made up some stuff.. The PET is blow moulded into a bottle shape??? no idea! is that question even in the syllabus??

I had no idea on that bread one.. 4 marks blank.. attempted the rest tho..
MC was bit harder than usual but ok - Q14 was brutal titrate NaoH and CITRIC ACID for one mark GET OUT i couldhnt even balance the equation lol randomly guessed B 41 or something.

So glad they only asked about one prac.. didnt draw a diag tho? And I FORGOT to draw one for AAS too i used the whole page 2 write.. screwed up molar heat question

ok that'll do lol. its all over! time for physics..:mad1:

 

[ct92]

Not as bad as it could have been, but the bread one was weird. I'll just hope for CFPE.

 

[GUSSSSSSSSSSSSS]

had to rush the AAS question and the last page on the electrochemical cell =[[[
but otherwise feelin pretty good about the exam xD

hope you all did as well as you wud have hoped =]]

 

[blabla91]

I was sure that pH adjustment occurred at 2 stages throughout the processes
1. Prior to flocculation this requires pH to be adjusted to basic conditions through the addition of lime or caustic soda, this is the only way flocculation can occur
2. As part of post treatment... however my reasoning was that adding Cl2 to water does this

Cl2 + H20 --> HOCl + HCl

hypochlorous then dissociates
HOCl + H20 --> OCl- + H3O+

thus the pH has been increased by the addition of chlorine, therefore either a) the chlorine addition does the pH adjustment or b) it has altered the pH and therefore pH adjustment has to occur after chlorination

for this reason i put B, i think its an unfair question

 

[Melisoverschool]

I think they may have to just mark them both right..seeing as sources say two different things

 

[GUSSSSSSSSSSSSS]

I think they may have to just mark them both right..seeing as sources say two different things

for some reason i think that is not an option lol


they'll just mark whichever one the question writer said was right

 

[sam5]

for some reason i think that is not an option lol


they'll just mark whichever one the question writer said was right

they have marked 2 mc correct in previous years in science papers. Maybe they will do it to us if we winge enough to them about conflicting textbooks!

 

[arjungamer123]

yeah i thought pH was last as well but the conquerin logic seems to be right aswell. dunnoooo

:mad1:

Jacaranda says pH balancing is last.

 

[cdiddy7]

I found it quite lovely
I expected something terrible, which I could not afford at all
But it was straight forward
I liked the COCl2 -> CO + Cl2 question, because im pretty strong with equilibrium
Loved the battery once I figured it out, but wasted time trying to start
Bread was really difficult, but I think I got it out
All the big markers were good
Multiple choice ruined me, had to guess a fair few, as I ran out of time for them
Forensics was so straight forward it was great
Forgot electrophoresis of food and test for alkanols, but besides that everything was good
BEST 7 MARKER EVER
It was so vague, you just had to say general obvious stuff
Overall, really good
I hope physics is similar

 

[danal353]

i think they'll mark both right - they've done it before

 

[nosh22]

Okie doke! Who's with me? Let's whinge! How do we contact BoS?

 

[boxhunter91]

I got it in my book.
These are the processes to sanitise water in order:
Screening
Aeration
Flocculation
Sedimentation
Filtration
Chlorination
pH adjustment
Fluoridation

 

[oliviaflynn2074]

i liked it!!!!!!!!!!!!!!!!!!!

 

[sam5]

Okie doke! Who's with me? Let's whinge! How do we contact BoS?

yep. Lets go! Demand that they mark both correct, cos textbooks cant make up their minds.

 

[Fortify]

Fail :'(