# Thoughts? (1 Viewer)

#### fishbulb

##### Member
JamesTockuss said:
I think the titre volume (23.45mL) was for the Na2CO3 ---- while the 25mL was for the HCl samples.
Yeh it was and i had the sodium carbonate concentration at 0.05M.

#### friction

##### Member
I got 0.1057 i think.

Also what did u guys get for that tablet question it was fucked.

#### uaiof100.00

##### New Member
I GOT 100% easily im so smart!

#### fishbulb

##### Member
friction said:
I got 0.1057 i think.

Also what did u guys get for that tablet question it was fucked.
I put 1.7mg and then divided it by 4 because i thought they used 4 tablets in the sample. oh well thats 1 mark gone

#### fishbulb

##### Member
friction said:
I got 0.1057 i think.

Also what did u guys get for that tablet question it was fucked.
Did u keep all your numbers in your calculator, that could be the cause of a slightly off answer.

#### friction

##### Member
Danz you are right just your are 10 x what you need. @ Fish bulb you did not factor in the 2:1 ratio therefor you got that not 0.1.

It is looking up now.

#### fishbulb

##### Member
friction said:
Danz you are right just your are 10 x what you need. @ Fish bulb you did not factor in the 2:1 ratio therefor you got that not 0.1.

It is looking up now.
Yeh i did bud.

Moles of Sodium Carbonate:

0.05 = Moles/0.02345

Therefore 2.345 x 10^-3 moles of HCL (Multiplying above answer by 2)

Molarity of HCL = (2.345 x 10^-3)/0.025

= 0.0938Mol/L

#### Zippora

##### Member
:::a::: said:
i do calculation questions in past papers, and then i somehow always manage to not be able to do them in the exam itself.

i found calculations in today's paper so confusing.

plus zinc tablets - wtf?
plus what were the 2 redox reactions in the shipwrecks option. one was ag+ + 2e- --> ag(s)
what was the other?
the other was the oxidation of water

#### friction

##### Member
fishbulb said:
Yeh i did bud.

Moles of Sodium Carbonate:

0.05 = Moles/0.02345

Therefore 2.345 x 10^-3 moles of HCL (Multiplying above answer by 2)

Molarity of HCL = (2.345 x 10^-3)/0.025

= 0.0938Mol/L
I think i did it very much differently to you. I cant remember the question however.

#### Zephyrio

##### Member
Fishbulb is correct for the titration question.

#### vulgarfraction

##### Member
I liked it, it was a lot less atrocious than "physics".

Yeah, heaps of calculations. I couldn't be stuffed to actually think for most of them, just dimension bashed- that way you can't possibly be wrong.

#### Daniel-08

##### New Member
fishbulb said:
Yeh i did bud.

Moles of Sodium Carbonate:

0.05 = Moles/0.02345

Therefore 2.345 x 10^-3 moles of HCL (Multiplying above answer by 2)

Molarity of HCL = (2.345 x 10^-3)/0.025

= 0.0938Mol/L
100% correct i remember i got this aswell
hey i think with the zinc question were meant to divide by 4 because there were 4 tablets dissolved?

#### fishbulb

##### Member
Daniel-08 said:
100% correct i remember i got this aswell
hey i think with the zinc question were meant to divide by 4 because there were 4 tablets dissolved?
sweet, i thought we might of, i didnt read the question well so i dunno.

#### Loganrah

##### New Member
The answer for the zinc question was 0.17 they clearly said AVERAGE absorbency, meaning that they had dissolved each of the tablets separately, measured their absorbency and averaged it.

##### Member
kayak2kayak00 said:
Jesus... I thought the extended response bits were pretty good but as for the calculations and the options? let's just not mention them
yeah i agree with that

#### Kearnzo

##### Member
Ahhhhhh I forgot to times by 2!! How could I forget that. I haven't got a moles questions wrong since like day 1. Pretty funny actually.

Anyone know what the question was out of? 2? Meh, they better carry errors in chem lol.

#### P.T.F.E

##### Member
JamesTockuss said:
I think the titre volume (23.45mL) was for the Na2CO3 ---- while the 25mL was for the HCl samples.
the titre was HCl the acid therefore it was 23.45 the Na2CO3 was 25ml so the answer was the .1057 or whatever

#### danz90

##### Active Member
Confuciousnesss over that stupid titration.

If we used the wrong titre volume, then its 1 mark lost - big deal. lol

#### timmiitippii

##### Member
I'm not gonna make some people feel bad by commenting on the difficulty of the paper. But i have to say that was the best paper i could of hoped for. No long winded essay questions that worth 6, 7 or 8 marks. Was so surprised when had to go through the paper to see so many calculations since i love calculations and only one single 7 marker in the industrial chem section. No 6 marker whatsoever.
I'm really glad we were given this paper though, after the shitness that was maths 3u adn 4u hsc exams and to an extent physics.

#### mick135

##### Member
aussiechick007 said:
yeah it seemed um... too good to be true!

hopefully that doesn't mean it"ll scale badly...
yeah it was very good i thought.
considering i was unprepared and not really ready for it.
they couldn't of made it easier on me

for industrial - do you think they'll notice i made up a cationic detergent "Mr Sheens carwash"?
haha i had no idea what to write for that 7 mark question.
i somehow related it back to solvay process and blabbed about that
anyways - good luck to you's all!