General thoughts: HSC chemistry 2015 (1 Viewer)

[Ekman]

But by checking from the same source multiple times you can determine whether there is a consistency in results + for it to be reliable it can be performed by other people but UNDER THE SAME CONDITIONS AND THE SAME LOCATION - Think about the measuring the value of G prac in physics; the value will vary on location and this kind of reflects that as well

Not sure if this makes sense though ...

Yeah but if we continue to take results from one pond, we cannot make a reliable judgment about the contamination site. Hence greater variety results must be taken into consideration in order to properly determine the effects of the contamination site. Remember, the aim of the experiment isn't about measuring lead concentrations of one pond, it was to measure the impacts of the contamination site, which involves taking more than one pond into consideration.

Edit: For example if Pond A says there is 50 ppm of lead present, and we keep on repeating the experiment on that one lake, and keep getting 50 ppm, how would we make a reliable judgment about the contamination site?

 

[halidida]

I put burette but how is it burette???

its meant to be the volumetric pippete right???, which transfers the standard solution (OF KNOWN CONCENTRATION). I accidentally selected burette (realised it when i was putting my booklets together that i circled burette not volumetric pippete)


I am an idiot. I forgot to label my axis on the graph. Now that means i can only get 1 or 2 /4 .

i did the exact opposite!!!!! i put pipette but meant burette

 

[Mr_Kap]

Overall i'm pretty pissed off that the exam was so easy --> around same difficulty as last years maybe. I know i probably only got 4/7 for industrial 7 marker I had a mind blank and forgot some stuff. I probably lost one mark on saponification cleaning one, and one mark on Solvay Process chemistry. So that's 20/25 for industrial.

The multiple choice i think i got 18/20 but i'm not sure i may have done stupid mistakes so ill just say 16/20.
The short answer: Bullshitted my way through the button cell --> only 2/4 for that.
Forgot axis on graph ---> 2/4 for that.
Crossed out my correct structure of citric acid and drew it wrong when i changed it last minute with like 5 minutes left. So 0/1.
UV one. Only expecting 2/3 even though I wrote everything i knew on that and i would give it 3/3, but im sure i missed somethin so 2/3.
Then another 5 or so marks on unexpected marking or something stupid i did wrong (even though im pretty sure i didnt make any other mistakes).

So overall i think i should get 85 raw. But taking into account the 5 "safety marks" i think i got 80/100 raw. Hopefully that can get me 87 examination mark.

 

[drakeisbaexo]

think i got band 6

 

[jeremydang]

Reliability is basically repeating the process to get a better approximation, what you are talking about is validity of the experiment.

 

[Mr_Kap]

I thought it was pipette? Dont you use the pipette to take a specific amt of primary standard out the volumetric flask into a conical flask, then drop by drop the burette which has the thing you dont know the concentration of??

yeh thats what im saying. I acidentally circled the wrong bubble and chose burette but its dfinitely the volumetric pipette. Thats the whole point of making a standard solution of KNOWN CONCENTRATION so we can find the concentration of whatever is in the burette

 

[Crisium]

Yeah but if we continue to take results from one pond, we cannot make a reliable judgment about the contamination site. Hence greater variety results must be taken into consideration in order to properly determine the effects of the contamination site. Remember, the aim of the experiment isn't about measuring lead concentrations of one pond, it was to measure the impacts of the contamination site, which involves taking more than one pond into consideration.

Edit: For example if Pond A says there is 50 ppm of lead present, and we keep on repeating the experiment on that one lake, and keep getting 50 ppm, how would we make a reliable judgment about the contamination site?

I need to see the question again maybe I'm missing something here

You're most probably right though because I suck at chem haha

 

[Loudvicuna]

yeh thats what im saying. I acidentally circled the wrong bubble and chose burette but its dfinitely the volumetric pipette. Thats the whole point of making a standard solution of KNOWN CONCENTRATION so we can find the concentration of whatever is in the burette

Its the burette bro

 

[I97]

Was that D?

Cant remember, possibly it was but can't recall it.

 

[Catz]

Cant remember, possibly it was but can't recall it.

Ok i remeber putting 30something so I'm not to sure which option it was

 

[Mr_Kap]

Its the burette bro

Its the burette. I was right the first time when i saw the quetion (and thought burette) and then i forgot to change it later. I AM SO HAPPY. TRUST YOUR GUT FEELING!!!!!!!!! WHY DID I DOUBT MYSKEF---> I WAS SO STUPID when i went and checked my exam luckily for me i didnt chang the answer

 

[malcolm21]

the only one that was a HFC which was A i think, Post the paper for everyone here big fella?

it was b

 

[Catz]

I messed up K the 3mrker, is it possible to at least get 1/3?

 

[Ekman]

I need to see the question again maybe I'm missing something here

You're most probably right though because I suck at chem haha

Or I could also be completely wrong as well.

 

[I97]

I messed up K the 3mrker, is it possible to at least get 1/3?

I messed it up too. If you at least wrote down the correct equlibrium expression (products over reactants using the chemical formulas) then that should be 1/3

 

[Fizzy_Cyst]

Yeah but if we continue to take results from one pond, we cannot make a reliable judgment about the contamination site. Hence greater variety results must be taken into consideration in order to properly determine the effects of the contamination site. Remember, the aim of the experiment isn't about measuring lead concentrations of one pond, it was to measure the impacts of the contamination site, which involves taking more than one pond into consideration.

Edit: For example if Pond A says there is 50 ppm of lead present, and we keep on repeating the experiment on that one lake, and keep getting 50 ppm, how would we make a reliable judgment about the contamination site?

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."

 

[Catz]

I messed it up too. If you at least wrote down the correct equlibrium expression (products over reactants using the chemical formulas) then that should be 1/3

OMG I DID THAT, Yes 1/3 lol

 

[Mr_Kap]

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.

 

[HecticLad]

yeh thats what im saying. I acidentally circled the wrong bubble and chose burette but its dfinitely the volumetric pipette. Thats the whole point of making a standard solution of KNOWN CONCENTRATION so we can find the concentration of whatever is in the burette

nah fam, doesnt matter what you put in the burette or flask, you still get the same values either way, the important part of the question was where it said "transfering into another solution", you pipette the solution into an empty flask where as with the burette you are transfering one solution to another

 

[malcolm21]

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.

c