HSC Chemistry Question Thread

[bridie_2345]

Hi there for the industrial chemistry option in saponification,  I'm confused about explaining how soap, water and oil act together as an emulsion?
I'm confused about how the micelles come into it aswell!
Thanks heaps!

[MisterNeo]

Hi there for the industrial chemistry option in saponification,  I'm confused about explaining how soap, water and oil act together as an emulsion?
I'm confused about how the micelles come into it aswell!
Thanks heaps!

Hey!
Water and oil are usually immiscible (don't mix) but can be made misicble using an emulsifying agent or emulsifier, which is soap.
An emulsion is basically two immiscible liquids dispersed throughout each other with the help of an emulsifier. Examples of emulsions include: milk, mayo, butter, etc.

You would need to know the role of soap's chemical structure.

The hydrophobic tail "adsorbs" to the oil to escape the water (it hates water), whereas the hydrophilic head stays out in the water (loves water). This forms a micelle.

The tiny droplets of oil are trapped in all these micelles. Notice how the heads are on the outside? The micelle is negatively charged, and repel each other to disperse themselves throughout the solution. Hence, becoming an emulsion and able to be washed away with water.
Hope this helps

[clarence.harre]

2007 doesn't have any marking guidelines.
Can you please let me know if I got it right? If I did, how could I condense it? If it's wrong, please point out where

(2007.29.d) 4 marks
Question:
The work of early scientists has increased our understanding of electron transfer
reactions. Describe the impact of this work on society.

Response:
Galvani's work catalysed Volta's development of the Galvanic Cell, leading to Davy's discovery of electrolysis and creation of stronger batteries, prompting Faraday's quantitative laws relating the charge transfer to the products produced.

This work has resulted in the ability to protect and conserve artefacts, benefiting society.

Electrolysis (electron transfer reactions) cleans and stabilises iron, copper and lead artefacts. They are placed in a dilute, alkaline solution (2% NaOH)  which acts an electrolyte between the cathode (artefact) and anode (inert steel). Using iron as an example:

   (anode): 4OH- <-> 2H2O + O2 + 4e-
(cathode): Fe(OH)Cl(s) + 2e- -> Fe(s) + OH- + Cl-

[bsdfjnlkasn]

2007 doesn't have any marking guidelines.
Can you please let me know if I got it right? If I did, how could I condense it? If it's wrong, please point out where

(2007.29.d) 4 marks
Question:
The work of early scientists has increased our understanding of electron transfer
reactions. Describe the impact of this work on society.

Response:
Galvani's work catalysed Volta's development of the Galvanic Cell, leading to Davy's discovery of electrolysis and creation of stronger batteries, prompting Faraday's quantitative laws relating the charge transfer to the products produced.

This work has resulted in the ability to protect and conserve artefacts, benefiting society.

Electrolysis (electron transfer reactions) cleans and stabilises iron, copper and lead artefacts. They are placed in a dilute, alkaline solution (2% NaOH)  which acts an electrolyte between the cathode (artefact) and anode (inert steel). Using iron as an example:

   (anode): 4OH- <-> 2H2O + O2 + 4e-
(cathode): Fe(OH)Cl(s) + 2e- -> Fe(s) + OH- + Cl-

Hey sorry, just wondering which topic this is relevant to because I don't recall learning about any of these chemists this year? :O

[Natasha.97]

Hey sorry, just wondering which topic this is relevant to because I don't recall learning about any of these chemists this year? :O

It's from the Shipwrecks option

[winstondarmawan]

2007 doesn't have any marking guidelines.
Can you please let me know if I got it right? If I did, how could I condense it? If it's wrong, please point out where

(2007.29.d) 4 marks
Question:
The work of early scientists has increased our understanding of electron transfer
reactions. Describe the impact of this work on society.

Response:
Galvani's work catalysed Volta's development of the Galvanic Cell, leading to Davy's discovery of electrolysis and creation of stronger batteries, prompting Faraday's quantitative laws relating the charge transfer to the products produced.

This work has resulted in the ability to protect and conserve artefacts, benefiting society.

Electrolysis (electron transfer reactions) cleans and stabilises iron, copper and lead artefacts. They are placed in a dilute, alkaline solution (2% NaOH)  which acts an electrolyte between the cathode (artefact) and anode (inert steel). Using iron as an example:

   (anode): 4OH- <-> 2H2O + O2 + 4e-
(cathode): Fe(OH)Cl(s) + 2e- -> Fe(s) + OH- + Cl-

Good answer, however I think you need more than one application for the four marks.
Maybe include the hydrolysis of water for obtain elemental Hydrogen and Oxygen?
Or more particularly, you can reference Davy's separation of salts from their compounds and how this is still used in society today to reconstitute these salts into new compounds and their uses. (e.g. KCl into KOH).

[bsdfjnlkasn]

It's from the Shipwrecks option

omg phew hahaha

[marshmallow.on.fire]

How should i go about working this out? The answer is B.   

[Natasha.97]

How should i go about working this out? The answer is B.   

Hi! I've attached the solution below:

Hope this helps

[clarence.harre]

Good answer, however I think you need more than one application for the four marks.
Maybe include the hydrolysis of water for obtain elemental Hydrogen and Oxygen?
Or more particularly, you can reference Davy's separation of salts from their compounds and how this is still used in society today to reconstitute these salts into new compounds and their uses. (e.g. KCl into KOH).

Thank you winstondarmawan
I hadn't even considered that.

[bsdfjnlkasn]

How would you write the equation for the oxidation of ammonia?

[Natasha.97]

How would you write the equation for the oxidation of ammonia?

Hi!

4NH_3(g) + 5O_2(g) → 6H₂O_(g) + 4NO_(g)

[J.B]

In the HSC course do we need to know about carbon branching (-yl) groups?

[bsdfjnlkasn]

In the HSC course do we need to know about carbon branching (-yl) groups?

Hey! The only thing I know about alkyl groups is that they function as chain stiffeners in polymers. The resulting plastic (if they have chain stiffeners) will be hard and rigid because of the intermolecular forces that act. For example, the additional Cl in PVC is electronegative, which then causes for dipole-dipole forces to act (i.e. attraction). This leads to a stiffer plastic as the polymer chains are held more tightly together.

[MisterNeo]

In the HSC course do we need to know about carbon branching (-yl) groups?

In terms of branching groups, you would probably only need to know how to name them when given a diagram. Like: methyl, ethyl, etc.
Other than that, there isn't much on them except for LDPE vs HDPE, and soaps in the industrial topic.