HSC 2012-2015 Chemistry Marathon (archive) (5 Viewers)

[AnimeX]

re: HSC Chemistry Marathon Archive

So solids don't affect the equilibrium, if they're removed/added? (in topics 1,2,3 - not industrial)

if you add a solid to a gas equilibrium, won't this decrease the volume?

 

[Menomaths]

re: HSC Chemistry Marathon Archive

So solids don't affect the equilibrium, if they're removed/added? (in topics 1,2,3 - not industrial)

if you add a solid to a gas equilibrium, won't this decrease the volume?

That's making an assumption because that's not the solid affecting the equilibrium per se, it's the decrease in volume that's affecting it.

.

 

[Menomaths]

re: HSC Chemistry Marathon Archive

How many isomers exist for C3H6F2?

 

[bedpotato]

re: HSC Chemistry Marathon Archive

How many isomers exist for C3H6F2?

4

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

4

yeh

 

[Menomaths]

re: HSC Chemistry Marathon Archive

The hydrogen carbonate ion is an amphiprotic species.
Write balanced chemical reactions showing it acting as an acid and a base.

 

[bangladesh]

re: HSC Chemistry Marathon Archive

HCO3 +H2O <---> H2CO3 + OH
HCO3 +H2O <---> CO3 + H3O


I didn't put charges because it'd look messy.

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

HCO3 +H2O <---> H2CO3 + OH
HCO3 +H2O <---> CO3 + H3O


I didn't put charges because it'd look messy.

it is wise to label which one is acting as a base and which is aciting as acid otherwise markers will give u zero!

 

[rednellav]

re: HSC Chemistry Marathon Archive

Marking guidelines are a bitch for chemistry. You guys just write down everything you know about the question topic or do you derive everything you have to speak about from the question's verb itself?

 

[freddo723]

re: HSC Chemistry Marathon Archive

What mass of sulfur is formed when 2L of sulfur dioxide is mixed with 2L of hydrogen sulfide under standard conditions (273K & 100Kpa) ?

 

[bangladesh]

re: HSC Chemistry Marathon Archive

it is wise to label which one is acting as a base and which is aciting as acid otherwise markers will give u zero!

yea yeah. i would have done so in the exam. just ceebs to do it here haha!

 

[bangladesh]

re: HSC Chemistry Marathon Archive

I think we've done enough guys. Goodluck to everyone! Hope you all do well.

 

[strawberrye]

re: HSC Chemistry Marathon Archive

Marking guidelines are a bitch for chemistry. You guys just write down everything you know about the question topic or do you derive everything you have to speak about from the question's verb itself?

In general, reading through marking guidelines allows you to familiarise yourself with what markers are looking for and enable yo to structure very strong answers It is a very good idea to understand all the exam verbs as well.

 

[teridax]

re: HSC Chemistry Marathon Archive

Thought I may revive this thread since I'm in my HSC currently with a few questions for marking that I hope anyone, whoever is great at chemistry can provide feedback on whether I need to expand on my info or make my answers more concise. (note: these were from the conquering chemistry textbook)


Q1. Why is it necessary to exclude air from catalytic and thermal cracking?

A. Because cracking occurs in the vapor phase which requires heat, so if oxygen is combined with the reactant, an explosion will occur.


Q2. Why do oil refineries carry out catalytic cracking?

A2. In order to turn long-chain hydrocarbons into smaller useful ones to increase efficiency during the process.


Q3. What is the difference between catalytic and thermal cracking? How do the experimental conditions differ for the two processes? What is the major purpose of each process?

A3. Catalytic cracking has a catalyst to break alkanes carried out at 500 degrees Celsius. It uses less heat than thermal cracking but cannot decompose large molecules into ethylene, so it does not meet the demands of the industry. Thermal cracking does not use a catalyst, only very high temperatures, between 700 to 1000 degress Celsius, whereby the use of steam allows for easy flow of hydrocarbon gases.

 

[Drsoccerball]

Chemistry marathon 2015

Since there is no Chemistry marathon I will make one.
The purpose of this thread is to post and answer questions that other members post.
Rules:
1) Answer the pending question before posting another question.
2) Ask questions that are in the syllabus.
3) Must be Chemistry related
4) Must mention amount of marks allocated to the question
5) With calculation questions please use Latex form
First question:

 

[Queenroot]

re: HSC Chemistry Marathon Archive

to make the bridge salty

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

to make the bridge salty

oh god....

 

[Queenroot]

re: HSC Chemistry Marathon Archive

To maintain neutrality within the electrochemical cell

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

To maintain neutrality within the electrochemical cell

AKA to complete the cell :L

 

[Queenroot]

re: HSC Chemistry Marathon Archive

AKA to complete the cell :L

ok