Section I: Short Answers (1 Viewer)

[danz90]

What did you think of short answer section?

I reckon it was pretty good this year. They could've made the ethanol one 7 marks instead of 5, but hey, im not complaining.

The way the put the water purifying question in there was a little different - asessing catchment area features, smart move by BOS.

A lot of calculations involved, which I was happy about, and no really long responses, which was good.

Overall, I am really happy with the paper.

 

[Aaron.Judd]

I thought it was pretty good as well, certainly easier than some of the previous years. Some of the caculations I', not so confident on though.

 

[JasonNg1025]

I failed the water one.
Option topic - O_O!!
NO NaOH, NO Solvay, heck, what's the environmental impacts of detergents??!!
Yeah, that's me in the exam

 

[independantz]

What did you guys write about for the water one?

 

[JasonNg1025]

I think I totally failed it... my friends wrote how agricultural activities, boating, <S>swimming</S>, and all that was prohibited, I wrote about what available equipment they have (sand or membrane filters) and what effects the water, for them to decide what they gotta do about it

 

[independantz]

I wrote about TDS and BOD due to animal faeces i.e the location of the catchment is important etc... and then described the process of removing the above. DIdn't really understand the q, that's the only q i had trouble with though so yeah...

 

[JasonNg1025]

Yeah, for the location I wrote about farms xD

EDIT: Well, I'm outta here, exam's over!

 

[Shadose]

I wrote about loose soil which increase the turbidity + fertilisers from farms. And their different treatments.

Ethanol was a nice present question.

 

[-::Sanni::-]

For the water I had run-off from agricultural activities (fertilisers/manure) and soil erosion.

I'm not sure about ethanol....I put the chemical equations: photosynthesis, fermentation, combustion. And they're cyclic therefore ethanol is carbon-neutral....

 

[r0kstar]

for the water one i put like diff features such as no vegetation = more suspended sediments that need to b filtered out (membrane filter)... dissolved solids need to evaporated out
that sulfates and phosphates from fertilisers from residential areas spawn bacteria S:S) whch then need sto b killed by chlorination....

 

[SpoonSamba]

I was confused with the galvanic cells question

the chlorine gas wtf? and the fact that the cathode was platinum confused me

made me so annoyed i was liek y couldnt u just b zinc n copper or something normal

so whatd u do with the platinum and chlorine?

 

[-::Sanni::-]

I put chlorine gas as the cathode. But now I'm having doubts! X_x Coz an electrode is a metal not a gas... crud!

 

[-::Sanni::-]

Calculations:
What was the answer to the question about Zinc and finding its mass in mg? I had no idea what to put for it X_x

 

[danz90]

I put chlorine gas as the cathode. But now I'm having doubts! X_x Coz an electrode is a metal not a gas... crud!

By definition a cathode is the site where electrons are accepted.
So the cathode is the Platinum, not the Chlorine.
IMO anyway..

 

[danz90]

Calculations:
What was the answer to the question about Zinc and finding its mass in mg? I had no idea what to put for it X_x

I got 0.16mg of Zinc.

Once you drew your graph with a line of best fit, you used the average absorbance, and then saw that 1.6mg/L was the average concentration.

then, since the sample was 100mL in volume, you multiply the concentration by volume, to get the mass.

1.6mg/L x 0.100L = 0.16mg

 

[-::Sanni::-]

Oh another thing!!!

What colour change was supposed to happen in the electrolytes of the glavanic cell?

 

[-::Sanni::-]

I got 0.16mg of Zinc.

Once you drew your graph with a line of best fit, you used the average absorbance, and then saw that 1.6mg/L was the average concentration.

then, since the sample was 100mL in volume, you multiply the concentration by volume, to get the mass.

1.6mg/L x 0.100L = 0.16mg

Oh damn! I was soooooooooo close!!! IF only I had more time.... Actually I didn't know that you could have mg/L as a concentration, but I was considering it in the exam... oh well!

I put down 1.6mg/L somewhere on the page. So hopefully that will mean 1 mark...

 

[danz90]

Oh another thing!!!

What colour change was supposed to happen in the electrolytes of the glavanic cell?

Well, I said that the Nickel Nitrate solution would become a darker green, as more Ni²⁺ would be formed, as the oxidation progressed, increasing the electrolyte concentration.

And in the other half-cell, no colour change would occur, since the KCl solution is colourless, and the formation of more Cl^- ions would not change the colour of the solution.

Oh damn! I was soooooooooo close!!! IF only I had more time.... Actually I didn't know that you could have mg/L as a concentration, but I was considering it in the exam... oh well!

I put down 1.6mg/L somewhere on the page. So hopefully that will mean 1 mark...

Yeah, I think it was 2 marks right?
You should get 1/2.. I reckon the conversion of mg/L to mg wouldve been the next mark.

 

[f(sex)]

Well, I said that the Nickel Nitrate solution would become a darker green, as more Ni²⁺ would be formed, as the oxidation progressed, increasing the electrolyte concentration.

And in the other half-cell, no colour change would occur, since the KCl solution is colourless, and the formation of more Cl^- ions would not change the colour of the solution.



Yeah, I think it was 2 marks right?
You should get 1/2.. I reckon the conversion of mg/L to mg wouldve been the next mark.

wouldnt the nickel migrate into the chlorine half cell and hence both will turn green?

 

[danz90]

wouldnt the nickel migrate into the chlorine half cell and hence both will turn green?

We'll i'd imagine that the salt bridge wouldn't allow that.