General thoughts: HSC chemistry 2015 (5 Viewers)

[I97]

im such an idiot i could of taken pictures of the whole exam for every to see...Like all parts.

I went to my chemistry teacher and was talking with him and going through the questions with him after the exam (he gets a copy of the exam after an hour after we started). The only multiple choice he still needed to figure out was the lead one. What was the answer to that btw. He said he eliminated A and D, so it was either B or C, but he said he needed more time to look at it because he only spent a few minutes on it.

I got the one with 9 was it 9.3 x 10^-3 g/L ?

 

[Mr_Kap]

Question states the following

"A sample of pond water from a contaminated site was analysed to determine the concentration of lead ions using the following procedure."

yeh im leaning towards what Ekman says. I was thinking that myself when doing the question but i ended up choosing A so i could just hurry up and move on (i started the multiple choice with like 30 minutes left and i still needed to do half the 7 marker in industrial, so i rushed through it)

 

[Librah]

Anyone remember what the exact q for industrial was?

 

[SlimiJay]

does someone have the paper? please upload or PM me

 

[HecticLad]

Anyone remember what the exact q for industrial was?

what one?

 

[Librah]

what one?

Determining K constant

 

[Ekman]

Question states the following

"A sample of pond water from a contaminated site was analysed to determine the concentration of lead ions using the following procedure."

yeh im leaning towards what Ekman says. I was thinking that myself when doing the question but i ended up choosing A so i could just hurry up and move on (i started the multiple choice with like 30 minutes left and i still needed to do half the 7 marker in industrial, so i rushed through it)

On second thought, the answer could be taking it from the same site, if we assume that the only purpose of the experiment is to measure contamination of lead ions on one pond. The only reason why I went with my reasoning is because of the word 'contamination site', meaning that the purpose of the experiment is to measure the impacts of the contamination site on ponds.

 

[Catz]

I wish the solvay process was the 7mrkr

 

[Crisium]

99 users oh my

Fizzy what do you think the answer was to that reliability question?

 

[Mr_Kap]

On second thought, the answer could be taking it from the same site, if we assume that the only purpose of the experiment is to measure contamination of lead ions on one pond. The only reason why I went with my reasoning is because of the word 'contamination site', meaning that the purpose of the experiment is to measure the impacts of the contamination site on ponds.

yeh well that was what i was debating about too. For validity/reliability questions you need to read the wording of the AIM VERY CAREFULLY. I obviously didnt have time to think about it much longer than like 40 seconds so i just chose A to move on.


Didn't EVER learn anion tests for the whole year ----> didnt pop up in any of my exams

Didn't learn the button cell or lead acid cell ---> didn't pop up in any of my exams apart from now .

Didn't learn any industrial chemistry pracs apart from saponification ---> payed off.

 

[leehuan]

 

[Crisium]

I wish the solvay process was the 7mrkr

Same

+ Did anyone else find the Solvay flow chart a bit dodgy

I find that ammonia recovery coming last seems more natural rather than having it before sodium carbonate formation

 

[Crisium]

Don't worry man I'm sure you did fine

Just put it behind you (You never have to do chem again ) and go all out for the remaining exams, we're almost there

 

[Hazabot]

Haha I'm probably the only one, but I did Biochem and it was brilliant. Other than 1 question about models, I might have aced it. (Biochem that is. Not the whole test)

Also, just because I like to crush dreams? Who put the answer to 10 as D? The incomplete combustion one?
The answer was A, although they did trick me at first.

Also I got 0.180 or 0.181 I cant remember for the NaOH and 46.something% for the sulphate.

The line graph was just connect the dots right?

Oh and what was the answer to 15? I put C since it was near an ocean and should have high dissolved solids, but it really depends on the tide whether it has high or low turbidity so Idk...

Also, would be interesting to hear what people answered in 24b, the Sulphate one, about how to improve it.

Good luck lads and ladesses.

P.S Im expecting/hoping for a raw mark of 88, anyone know what that aligns to? I hope it's a band 6.

EDIT: Corrected multiple choice question

 

[Mr_Kap]

Same

+ Did anyone else find the Solvay flow chart a bit dodgy

I find that ammonia recovery coming last seems more natural rather than having it before sodium carbonate formation

no way. I learnt solvay process in the 20 minutes before i went in to the exam.
Was lucky the questions were easy for that

 

[helloimyellow]

On second thought, the answer could be taking it from the same site, if we assume that the only purpose of the experiment is to measure contamination of lead ions on one pond. The only reason why I went with my reasoning is because of the word 'contamination site', meaning that the purpose of the experiment is to measure the impacts of the contamination site on ponds.

Yes this was what I thought. They didnt say there was only one pond so I believed that there could be many ponds in that contamination site.

 

[apurba]

how many marks am i going to lose for reading citric acid as acetic acid for the 4 mark titration calculation question?

 

[Crisium]

Haha I'm probably the only one, but I did Biochem and it was brilliant. Other than 1 question about models, I might have aced it. (Biochem that is. Not the whole test)

Also, just because I like to crush dreams? Who put the answer to 10 as D? The incomplete combustion one?
The answer was A, although they did trick me at first.

Also I got 0.180 or 0.181 I cant remember for the NaOH and 46.something% for the sulphate.

The line graph was just connect the dots right?

Oh and what was the answer to 17? I put C since it was near an ocean and should have high dissolved solids, but it really depends on the tide whether it has high or low turbidity so Idk...

Also, would be interesting to hear what people answered in 24b, the Sulphate one, about how to improve it.

Good luck lads and ladesses.

P.S Im expecting/hoping for a raw mark of 88, anyone know what that aligns to? I hope it's a band 6.

Yeah I'm interested to hear what others put as well

I talked about giving more time for the ground up fertiliser to dissolve in the hydrochloric acid (They mentioned that the Barium chloride is added in excess quickly after that)

+ Using a sintered glass filter since the barium sulphate precipitate can occurs in really small amounts and so a conventional filter paper wouldn't do much

 

[HecticLad]

Haha I'm probably the only one, but I did Biochem and it was brilliant. Other than 1 question about models, I might have aced it. (Biochem that is. Not the whole test)

Also, just because I like to crush dreams? Who put the answer to 10 as D? The incomplete combustion one?
The answer was A, although they did trick me at first.

Also I got 0.180 or 0.181 I cant remember for the NaOH and 46.something% for the sulphate.

The line graph was just connect the dots right?

Oh and what was the answer to 17? I put C since it was near an ocean and should have high dissolved solids, but it really depends on the tide whether it has high or low turbidity so Idk...

Also, would be interesting to hear what people answered in 24b, the Sulphate one, about how to improve it.

Good luck lads and ladesses.

P.S Im expecting/hoping for a raw mark of 88, anyone know what that aligns to? I hope it's a band 6.

Conquering chem textbook had a mad part on the fertiliser experiment, i wrote slowly adding the BaCl to a heated solution of the dissolved fertiliser will produce larger precipitate crystals, this means that there will be less precipitate lost through the filter, also less ions from the solution will adsorb onto the precipitate crystals due to less surface area so it would be closer to the real value, also wrote that the solution should be cooled in an ice bath after precipitation to reduce the solubility of BaSO4, and finally rinsing the filtrate with 4 lots of 5ml water will remove and contaminants on the surface of BaSO4 without compromising solubilty, and then rinsing with 5ml ethanol to aid in the drying process

 

[Mr_Kap]

Gotta go get a band 6 in physics now... fuck.

Ever since i stuffed up 2u math (think i got 93/94 raw) --> was thinking of getting like 97 aligned before the 2u exam (like in past HSC papers when i compared my raw mark), but now it will only be like 95 aligned. (BTW i changed my math predictions in my sig. after the exam).

Then i said i was gonna get band 6 today but nup. Stupid mistakes like not labelling axis on the graph etc.. are gonna cost me.

.

at least i have 3.5 days to rote learn all the theory dot points in physics (am comfortble with the understanding and calculation qustions)