Predictions for Chemistry 2014 HSC? (5 Viewers)

[enigma_1]

Ok QZP, how does this go
- A buffer is a substance which works to minimise fluctuations in pH if small quantities of acids or bases are adding (not strictly necessary to answer the question, I want to put this in regardless)
- Generally comprised of a weak acid and its conjugate base (but can be vice-versa)
- The bicarbonate ion, found in human blood, works to maintain a pH of 7.4 to within a 0.5pH range if acidic or basic substances enter the blood stream.
- H2CO3 <----> HCO3- + H+
- The buffer system works as, in accordance with LCP, addition of an acidic substance shifts the equilibrium to the left in order to reduce the impact of the acidification and thus prevent acidemia. By contrast, addition of a basic substance pushes the equilibrium to the right and favours the production of H+ ions, thus restoring pH and preventing alkylosis.

yeah das good 4/4

although it's short, it's concise

probably use the equation faisalabdul16 wrote above, and explain it in terms of that as it shows depth of knowledge BUT not necessary

 

[SuchSmallHands]

yeah das good 4/4

although it's short, it's concise

probably use the equation faisalabdul16 wrote above, and explain it in terms of that as it shows depth of knowledge BUT not necessary

Could even go all out if you wanted, and give you:
CO2 + H2O <---> H2CO3 <----> HCO3- + H+
But it wasn't too necessary for the question and the quicker I finished that question the quicker I could reward myself with cheese. And yeah, I'm a dot point kind of person. Long responses just don't work for my brain in chem (I do legal and modern, I have enough of that in my life).

 

[SuchSmallHands]

New question anyone?

 

[QZP]

Ok QZP, how does this go
- A buffer is a substance which works to minimise fluctuations in pH if small quantities of acids or bases are adding (not strictly necessary to answer the question, I want to put this in regardless)
- Generally comprised of a weak acid and its conjugate base (but can be vice-versa)
- The bicarbonate ion, found in human blood, works to maintain a pH of 7.4 to within a 0.5pH range if acidic or basic substances enter the blood stream.
- H2CO3 <----> HCO3- + H+
- The buffer system works as, in accordance with LCP, addition of an acidic substance shifts the equilibrium to the left in order to reduce the impact of the acidification and thus prevent acidemia. By contrast, addition of a basic substance pushes the equilibrium to the right and favours the production of H+ ions, thus restoring pH and preventing alkylosis.

An ion works to maintain a pH? not quite. Do you guys understand why we need the conj. base?

 

[faisalabdul16]

Enigma and SSH 4/4

3. The molar heat of combustion of ethanol is 1367kJ/mol
What mass of ethanol is required to heat 1.0 moles of water by 10 degrees.

a - 136.7g
b - 46.0g
c - 25.3g
d - 0.025g

 

[SuchSmallHands]

An ion works to maintain a pH? not quite. Do you guys understand why we need the conj. base?

*Bicarbonate ion buffering system, just a typo man haha

 

[QZP]

c

 

[QZP]

*Bicarbonate ion buffering system, just a typo man haha

HCO3 CO3 system? Best explicitly say it i.e. H2CO3 - HCO3 system. SCRUTINY!!!!

 

[faisalabdul16]

c

Nope.

Anyone else tried the multiple choice?
I really liked it.

 

[QZP]

Nope.

Anyone else tried the multiple choice?
I really liked it.

d

 

[SuchSmallHands]

HCO3 CO3 system? Best explicitly say it i.e. H2CO3 - HCO3 system. SCRUTINY!!!!

I think convention is to name the system based on the weak acid/base, but OKAY I'LL DO THAT NEXT TIME haha

 

[SuchSmallHands]

Nope.

Anyone else tried the multiple choice?
I really liked it.

No I didn't even see it, give me one sec..

 

[QZP]

fml i have terrible mcq skills. PHYS trials: 14/20 in mcq and 78/80 in short answers

 

[faisalabdul16]

d

yeap

 

[SuchSmallHands]

fml i have terrible mcq skills. PHYS trials: 14/20 in mcq and 78/80 in short answers

Same here! Multiple choice kills me every time.

 

[enigma_1]

LOL someone help, you know how you have mCAT, what are the units for all of them? I also got c coz I don't know the units for that stuff.

Thankssss

 

[faisalabdul16]

LOL someone help, you know how you have mCAT, what are the units for all of them? I also got c coz I don't know the units for that stuff.

Thankssss

 

[zhertec]

I still haven't finished my notes for chem >.< I'm guessing everyone else has finished?

 

[enigma_1]

Fkin omg now I have to turn on my computer

*facepalm*

 

[faisalabdul16]

I still haven't finished my notes for chem >.< I'm guessing everyone else has finished?

Dude you should be ahead of us all and get a higher mark then all of us.

Idk about anyone else but my mentality for those who accelerate is that they should blitz the subject.

Year 11 is a bludge. You have a whole year to prep for 1 subject.

Meanwhile in year 12, you have at least 4 other subjects.