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HSC 2012-2015 Chemistry Marathon (archive) (4 Viewers)

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Mr_Kap

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re: HSC Chemistry Marathon Archive

Solids and liquids. Don't forget about the liquids, as they are not counted in the K constant as well.
does that include (aq)??? or just (L)??
 

aanthnnyyy

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Did anyone find 2014 paper relatively easy? I just did it (without doing it before) and found my mark with a big surprise on my face
 

Mr_Kap

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Did anyone find 2014 paper relatively easy? I just did it (without doing it before) and found my mark with a big surprise on my face
Did you mark it really hard?

Because thats how they marked it last year. Look at the exam thoughts forum for last year and everyone thinking they gonna get 90% raw mark (including my brother)..

Nek min, they get scaled 80's. Which is like raw mark in the 70's. Last year was an easy test..very easy...so they marked to EVERY LITTLE DETAIL last year. Teacher marked a question last year and he confirmed it
 

leehuan

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Always mark yourself extremely harshly and criticise yourself for every tiny little mistake you make.

Because I get biased marking my own work, I give it to other people to mark for me. Much more secure means.
 

Drsoccerball

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Always mark yourself extremely harshly and criticise yourself for every tiny little mistake you make.

Because I get biased marking my own work, I give it to other people to mark for me. Much more secure means.
This is so true LOL
 

InteGrand

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If the test is ever easy, it's compensated for by crazy harsh marking haha.
 

aanthnnyyy

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nah I did mark harsh guys, I'm never easy on myself, BUT as Kap said, since it was relatively easier, I'd assume the marking was pin-point-razer-blade harsh, with every little wrong word costing a mark
 

Mr_Kap

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re: HSC Chemistry Marathon Archive

Let's keep this going:

Describe the diferences in the structure and properties of Ozone and O2. 3 Marks
 

kawaiipotato

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Let's keep this going:

Describe the diferences in the structure and properties of Ozone and O2. 3 Marks
Ozone and O2 have similar physical properties due to their similar molecular weight. Thus, they have similar intermolecular (dispersion) forces and causes them to require similar amounts of energy input in order to break these forces. Thus, ozone and O2 have similar physical properties (boiling point, melting point). However, they have different chemical properties due to their polarities. Since O2 is a linear molecule, it is relatively ... (forgot that word), making it non-polar, non-reactive and less soluble in water. Ozone is a 'bent' molecule, making it more polar and hence, more reactive and soluble in water.
 

Crisium

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re: HSC Chemistry Marathon Archive

Ozone and O2 have similar physical properties due to their similar molecular weight. Thus, they have similar intermolecular (dispersion) forces and causes them to require similar amounts of energy input in order to break these forces. Thus, ozone and O2 have similar physical properties (boiling point, melting point). However, they have different chemical properties due to their polarities. Since O2 is a linear molecule, it is relatively ... (forgot that word), making it non-polar, non-reactive and less soluble in water. Ozone is a 'bent' molecule, making it more polar and hence, more reactive and soluble in water.
Should probably disregard the similarities since the question directly refers to differences - If it were a compare question then yeah that would be fine

Should also mention the difference in chemical stability; ozone has a lower chemical stability than O2 since the coordinate covalent bond requires much less energy (i.e. a lower bond energy) to break and will thus readily decompose into oxygen and an oxygen free radical (Usually by UV light, you should be familiar with the equation) - > this also means that ozone has a greater oxidising strength. Ozone has a higher boiling point than oxygen due to its greater molecular mass -> more dispersion forces -> more energy required

And perhaps mention a suitable use at the end if you have space, such as welding for oxygen and disinfectant for ozone
 

Mr_Kap

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re: HSC Chemistry Marathon Archive

ive been doing bio since last tuesday that i've forgotten some chemistry.

Need to sharpen up:

"
 

Crisium

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Next question:

John Smith walks into a shopping centre and all of a sudden "Suprise mother fucker" someone throws concentrated sulphuric acid on his torso.

He sees a stand with bottles of cold water and another stand with packets of sodium bicarbonate (aka sodium hydrogen carbonate)

If you were John which would you use? Justify your answer (1 Mark)
 

Mr_Kap

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re: HSC Chemistry Marathon Archive

Next question:

John Smith walks into a shopping centre and all of a sudden "Suprise mother fucker" someone throws concentrated sulphuric acid on his torso.

He sees a stand with bottles of cold water and another stand with packets of sodium bicarbonate (aka sodium hydrogen carbonate)

If you were John which would you use? Justify your answer (1 Mark)
lmao. can't stop laughing. :lol: :lol: :lol: :lol: :lol: I see John Smith and expecting some contribution of chemists or some shit and then that happens!!

If i was John i would put a shit load of sodium hydrogen carbonate on my torso, and embrace the white powder. I would use this over water as water ionises with sulfuric acid in an exothermic reaction, and would give me one hell of a burn, and doesn't neutralize the acid to safe levels. Sodium Hydrogen Carbonate however is amphiprotic meaning it is used to neutralize acid and base spills, or neutralise a torso to safe ph levels when someone shouts "Suprise Motherfucker" and throws concentrated H2SO4 on you. Next, i would proceed to chase the idiot that did this to me, and then make an ester out of him
 
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Crisium

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re: HSC Chemistry Marathon Archive

lmao. can't stop laughing. :lol: :lol: :lol: :lol: :lol: I see John Smith and expecting some contribution of chemists or some shit and then that happens!!

If i was John i would put a shit load of sodium hydrogen carbonate on my torso, and embrace the white powder. I would use this over water as when water ionises with sulfuric acid, and would give me one hell of an acid burn, and doesn't neutralize the acid to safe levels. Sodium Hydrogen Carbonate however is amphiprotic meaning it is used to neutralize acid and base spills, or neutralise a torso to safe ph levels when someone shouts "Suprise Motherfucker" and throws concentrated H2SO4 on you. Next, i would proceed to chase the idiot that did this to me, and then make an ester out of him
Oh crap I used the wrong acid gg

I wanted people to realise that using the sodium hydrogen carbonate will cause a neutralisation reaction which is EXOTHERMIC so the water is preferred ...
 

Mr_Kap

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yeh wel sulfuric acid with water is highly exothermic (industrial chemistry)
 

Crisium

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yeh wel sulfuric acid with water is highly exothermic (industrial chemistry)
Yeah I do Industrial haha, I probably should have put concentrated acetic acid or something along the lines of that
 

Mr_Kap

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Yeah I do Industrial haha, I probably should have put concentrated acetic acid or something along the lines of that
Can you explain why water would be better for that please? :)
 
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