Predictions for Chemistry 2014 HSC? (7 Viewers)

[Queenroot]

that's so rood. i wouldn't refuse advice cos you didn't get a B6.

I would refuse advice cos you're square.

ur rude

 

[faisalabdul16]

The joys of doing a bio paper and answering the chem questions you guys put up
more pls

 

[seventhroot]

The joys of doing a bio paper and answering the chem questions you guys put up
more pls

needs questions spoon fed to him

gg no re

 

[Queenroot]

The joys of doing a bio paper and answering the chem questions you guys put up
more pls

explain protein synthesis from chemical viewpoint

gg no re

 

[faisalabdul16]

explain protein synthesis from chemical viewpoint

gg no re

nao keep this chemistry, no bio in here

 

[Queenroot]

nao keep this chemistry, no bio in here

What is heat of combustion

 

[faisalabdul16]

What is heat of combustion

Energy released when a compound undergoes combustion (burns)

Properrrrr pls

 

[Queenroot]

Energy released when a compound undergoes combustion (burns)

Properrrrr pls

What is your option topic?

In the meantime:

Name this

 

[emilios]

What is your option topic?

In the meantime:

Name this

1,3-dimethyl-2-ethyl-1,4-pentadiene

 

[photastic]

1,3-dimethyl-2-ethyl-1,4-pentadiene

It has 6 carbons, not 5

 

[Queenroot]

1,3-dimethyl-2-ethyl-1,4-pentadiene

It has 6 carbons, not 5

.

 

[emilios]

.

lel dun goofed.

2,4-dimethyl-1,3-hexadiene

 

[Queenroot]

lel dun goofed.

2,4-dimethyl-1,3-hexadiene

Yay!
That was quite a tricky one. Always remember to look for the longest chain.

What is your option topic?

 

[faisalabdul16]

Yay!
That was quite a tricky one. Always remember to look for the longest chain.

What is your option topic?

Industrial

 

[photastic]

lel dun goofed.

2,4-dimethyl-1,3-hexadiene

Perf answer. Band 6

 

[Queenroot]

Evaluate how environmental issues are addressed in the Solvay process.

 

[faisalabdul16]

Evaluate how environmental issues are addressed in the Solvay process.

Do this pedigree question and tell me what you get!
http://community.boredofstudies.org/attachment.php?attachmentid=30959&d=1411817956

also, have not revised last two dot points of industrial yet (solvay or saponification) someone else answer the question

 

[QZP]

Ozone depletion occurs because of chlorofluorocarbons. Chlorofluorocarbons are alkane molecules with the hydrogens replaced with chlorine or fluorine molecules. In the troposphere these chemicals are extremely stable, chemically inert and unreactive. They are non-corrosive chemicals which were originally used to replace ammonia as refrigerants and in air conditioners. When chlorofluorocarbons leak into the atmosphere they travel up to the stratosphere and cause ozone depletion as strong uv Rays split the molecule forming free radicals.

CClF2 + UV ----> Cl(radical) + CF2 (radical)
Cl + O3 ---> ClO (radical) + O2
ClO radical + oxygen radical ---> Cl radical plus oxygen

As apparent, chlorofluorocarbons cause ozone depletion and during the process the chlorine radical is regenerated and known as a catalyst. One chlorine radical can destroy thousands of ozone molecules before being removed by methane

- Bold 1: Poor leading sentence. Ozone depletion is caused by various substances not only CFC's which is what you implied
- Red: Useless
- Bold 2: Poor cause and effect (I know what you're trying to say, but it's not simply that free radicals directly cause ozone depletion)
- Overall: Poor answer because you didn't really tackle what is causing ozone depletion. All you said is CFC's destroy ozone. Sure, but overall the effect could be nil since the ozone layer is always naturally regenerating. (I.e. say that the increase in usage of ozone depleting substances has resulted in the rate of ozone destruction > rate of ozone regeneration and hence the phenomena "ozone depletion")

Cut down on why CFC's are used, unnecessary. You didn't define what Ozone depletion is. I would give it 4/6.

+1 (not on mark though)

 

[emilios]

Evaluate how environmental issues are addressed in the Solvay process.

Oo I'm a little rusty with Solvay but i'll bite (without looking through my notes!)

The Solvay Process describes the industrial conversion of the raw materials ammonia, limestone and brine into sodium carbonate over a series of steps. The net chemical reaction that occurs is;
NaCl + CaCO3 --> Na2CO3 + CaCl2

While there is some market for the calcium chloride byproduct, the supply exceeds the demand. This is an issue as if it is dumped into rivers and waterways it can significantly increase the level of TDS, hence reducing water quality and negatively affecting the natural ecosystem. This issue is addressed through delivering the calcium chloride waste into a 'settling pond' where it does not affect local water systems. The water used during the formation of NaHCO3 in the Solvay process is heated to high temperatures, and can cause thermal pollution if dumped in rivers and waterways, resulting in decreased oxygen solubility and threatening aquatic life. Hence, the water used in the process must be sufficiently cooled before being discharged into the environment. The Solvay process is efficient in the sense that the majority of the raw materials (such as ammonia) are recycled and thus resource depletion is kept to a minimum (?)

Guys I feel like I know most of the Chem concepts but my articulation is terrible. I really don't want to lose marks cos of how I phrase things I need your help, plz gib more practice questions

 

[Queenroot]

Oo I'm a little rusty with Solvay but i'll bite (without looking through my notes!)

The Solvay Process describes the industrial conversion of the raw materials ammonia, limestone and brine into sodium carbonate over a series of steps. The net chemical reaction that occurs is;
NaCl + CaCO3 --> Na2CO3 + CaCl2

While there is some market for the calcium chloride byproduct, the supply exceeds the demand. This is an issue as if it is dumped into rivers and waterways it can significantly increase the level of TDS, hence reducing water quality and negatively affecting the natural ecosystem. This issue is addressed through delivering the calcium chloride waste into a 'settling pond' where it does not affect local water systems. The water used during the formation of NaHCO3 in the Solvay process is heated to high temperatures, and can cause thermal pollution if dumped in rivers and waterways, resulting in decreased oxygen solubility and threatening aquatic life. Hence, the water used in the process must be sufficiently cooled before being discharged into the environment. The Solvay process is efficient in the sense that the majority of the raw materials (such as ammonia) are recycled and thus resource depletion is kept to a minimum (?)

Guys I feel like I know most of the Chem concepts but my articulation is terrible. I really don't want to lose marks cos of how I phrase things I need your help, plz gib more practice questions

Why does TDS effect marine life/water quality? Elaborate.

You did answer the question on point however. So that's a good call.