Predictions for Chemistry 2014 HSC? (3 Viewers)

[faisalabdul16]

lol, thread needs to be renamed 2014 Pre-HSC Marathon Thread

Indeed it does. Hahaha, it's really good though

 

[timeflies]

Outline the steps required in producing a standard solution and justify the choice of solid you use.

1. Calculate the mass of anhydrous sodium carbonate required to prepare a certain volume and concentration of the solution.
2. Measure this mass of the solid on pre-weighed filter paper with an electronic balance.
3. Transfer the solid into a beaker with distilled water and stir with stirring rod until dissolved.
4. Transfer solution from beaker into a volumetric flask of the volume you require with rinsed glass funnel.
5. Rinse beaker and stirring rod with distilled water and transfer this water into flask as well.
7. Add distilled water until just under the line. Then add distilled water via a dropper until bottom meniscus hits the line.
8. Stopper flask and shake to mix.

Anhydrous sodium carbonate was the chosen solid as it is stable in the air, highly soluble in water and of high purity. Other substances have changing concentrations as they do not possess the same qualities as anhydrous sodium carbonate (eg. NaOH and H2SO4 absorb water from the air adding to their weight). These substances would lead to inaccuracies and low reliability when used in titrations as their concentration would not be definite.

New Question: Assess the validity and accuracy of the evidence for increasing concentrations of oxides of sulfur and nitrogen in the atmosphere.

 

[faisalabdul16]

1. Calculate the mass of anhydrous sodium carbonate required to prepare a certain volume and concentration of the solution.
2. Measure this mass of the solid on pre-weighed filter paper with an electronic balance.
3. Transfer the solid into a beaker with distilled water and stir with stirring rod until dissolved.
4. Transfer solution from beaker into a volumetric flask of the volume you require with rinsed glass funnel.
5. Rinse beaker and stirring rod with distilled water and transfer this water into flask as well.
7. Add distilled water until just under the line. Then add distilled water via a dropper until bottom meniscus hits the line.
8. Stopper flask and shake to mix.

Anhydrous sodium carbonate was the chosen solid as it is stable in the air, highly soluble in water and of high purity. Other substances have changing concentrations as they do not possess the same qualities as anhydrous sodium carbonate (eg. NaOH and H2SO4 absorb water from the air adding to their weight). These substances would lead to inaccuracies and low reliability when used in titrations as their concentration would not be definite.

New Question: Assess the validity and accuracy of the evidence for increasing concentrations of oxides of sulfur and nitrogen in the atmosphere.

hahaha i ceebs doing this question, evidence though
- Photochemical smog
- increased acidity in waterways
- erosion of limestone monuments in America.

 

[faisalabdul16]

Industrial Question

Account for the cleaning action of soap by describing its structure.

Soap is an effective surfactant due to its unique tad-pole like structure which allows for two-pronged cleaning effects. The anionic head is described as being hydrophilic (water loving) whilst the hydrocarbon tail is described as being hydrophobic (water hating). By working together, soap is able to act as a bridge, carrying off particles as the tail attaches to oil particles and as the anionic head dissolves in water. By effectively encircling the oil particles, a micelle is formed. The micelle carries a negative charge and as such, is unable to resettle at the surface as the particles repel one another. Non-oily substances can still be removed as the head is dissolved in water, and as the tail sticks up in the air, thereby breaking the surface tension. This effectively makes the particles "more wet", and thus, they wash off.

ROTE LEARN LOL.

 

[mreditor16]

FA16, Chem is so going to lift your atar.

 

[faisalabdul16]

FA16, Chem is so going to lift your atar.

Notsureifsrs or sarcastic.

English is. Me improving marks in any subject besides english, will marginally improve my atar. Whereas english, improving in that will boost my atar.

Hence why i have written 23412412341234 essays so far.

haha nah i wrote 8 or 9 essays last week, exposing myself to different questions.

 

[mreditor16]

no legit. from what I briefly see, your chem knowledge is astounding

 

[photastic]

no legit. from what I briefly see, your chem knowledge is astounding

Then there's the rest, still partying for the best :O

 

[anomalousdecay]

FA16, Chem is so going to lift your atar.

Its fasadabubsibauadul.

 

[faisalabdul16]

Then there's the rest, still partying for the best :O

bold part - ? hahaha

no legit. from what I briefly see, your chem knowledge is astounding

thanks

 

[someth1ng]

Notsureifsrs or sarcastic.

English is. Me improving marks in any subject besides english, will marginally improve my atar. Whereas english, improving in that will boost my atar.

Hence why i have written 23412412341234 essays so far.

haha nah i wrote 8 or 9 essays last week, exposing myself to different questions.

Pretty much what happened to me - if I had increased my English mark by like, 5, I would probably have gotten into the 98s (from 96.50).

 

[faisalabdul16]

Pretty much what happened to me - if I had increased my English mark by like, 5, I would probably have gotten into the 98s (from 96.50).

Yeap! Something i realised while playing around with atar calculators and looking at the statistics UAC provides.

 

[faisalabdul16]

This thread must not die lel

Environmental problems of the Solvay process?

 

[Queenroot]

Pretty much what happened to me - if I had increased my English mark by like, 5, I would probably have gotten into the 98s (from 96.50).

Must stop derailing

 

[faisalabdul16]

Must stop derailing

This thread died. No one answers

 

[mreditor16]

This thread died. No one answers

it had a good run! come over to the hsc economics marathon

 

[faisalabdul16]

it had a good run! come over to the hsc economics marathon

hahaha i remember a fair amount of work from the prelim course

internal and external economies of scale
Diseconomies of scale
Tightening and loosening of Monetary Policy. hahahah

 

[faisalabdul16]

OKAY FASABAULAHAH

I have memorised the chemistry course now (about bloody time). Bring it on.

(I don't do industrial btw haha)

HAHAHA yes someone to discuss with!

Hmmmm

The voltage between X and Y is 1.56, however experiment conducted displayed a voltage of 1.26.
Why? Provide 3 reasons.

 

[faisalabdul16]

1) The standard galvanic cell conditions weren't used. Standard conditions involve a inert platinum electrode immersed in 1.0 mol/L HCl with Hydrogen gas bubbled in at 100 kPa and 25 degrees Celsius
2) Low concentrations were being used so there were less cations to gain electrons and travel through the external circuit towards the cathode, thus producing a lower experimental potential difference than the theoretical value
3) Metals not completely pure (were they cleaned with emery paper beforehand) or impurities in electrolyte solutions.

If the third point isn't valid enough, some bs about how low quality voltmeters were used which put load on the external circuit thereby reducing potential voltage and/or the person observing was like close to blind etc

ask a question

 

[QZP]

Do you really think its nice? idk man that's like a 1/3 to me