Preliminary 2012 Chemistry Marathon (3 Viewers)

[planino]

Nope you don't really do it in depth other than nuclear decay and production and uses of radioisotopes.

meh sounds good enough

 

[Kimyia]

I LOVED doing nuclear chem this year. True, you don't do much on it but you cover alpha, beta, and gamma radiation, production/uses of radioisotopes, ways to measure radiation, and my favourite your decay equations

 

[theind1996]

I LOVED doing nuclear chem this year. True, you don't do much on it but you cover alpha, beta, and gamma radiation, production/uses of radioisotopes, ways to measure radiation, and my favourite your decay equations

can't wait for da first topic. petroleum YEAYEA. apparently (production of materials, i think that's what it's called) has a lot of memorising. Y/N?

 

[Kimyia]

can't wait for da first topic. petroleum YEAYEA. apparently (production of materials, i think that's what it's called) has a lot of memorising. Y/N?

Yes I would say it has quite a bit of memorising. Like the properties and uses of different polymers, knowing everything there is to know about ethanol and cellulose, unfortunately having to memorise everything there is to know about a biopolymer of your choice, but the worst of memorising - the structure, chemistry, cost and practicality of two types of electrochemical cells. But after a while of revising, most of it pretty much becomes second nature so it gets easier

 

[theind1996]

Yes I would say it has quite a bit of memorising. Like the properties and uses of different polymers, knowing everything there is to know about ethanol and cellulose, unfortunately having to memorise everything there is to know about a biopolymer of your choice, but the worst of memorising - the structure, chemistry, cost and practicality of two types of electrochemical cells. But after a while of revising, most of it pretty much becomes second nature so it gets easier

so there's no logic/understanding behind it? 90% memorising?

 

[Kimyia]

so there's no logic/understanding behind it? 90% memorising?

There is logic and understanding behind it - like logic will give you the reasons for why you'd use ethanol instead of petrol, and you can usually just BS the properties and uses of polymers, and a lot of nuclear chem is just logic. Just depends on how much the topic makes sense to you. Maybe 60% memorising? But if you like the petroleum sort of stuff, then a lot more of it would just be logic for you and less memorising.

 

[bleakarcher]

Revive!!

 

[skillstriker]

Metal - Francium

http://www.youtube.com/watch?v=SjowQJMS-W4

List method during the decomposition of AgCl practical and list any safety issues and all equipment (7 marks)

- equipment: filter paper, newspaper, cardboard, scissors, silver nitrate, sodium halides (sodium chloride, sodium bromide, sodium iodide etc.), petri dishes, sodium thiosulfate
- safety issues: hand may come in contact with the silver nitrate, paper cut, cutting yourself with scissors.
- method: silver halides were produced by immersing filter paper in silver nitrate and then one of the salts. This was repeated for each of the salts and they were placed on top of the newspaper. stiff cardboard was cut into shapes, which were placed on top of the filter papers. The experiment was left exposed to sunlight and observations were recorded the following day. sodium thiosulfate used to prevent further decomposition
- results: the silver halides decomposed into silver metal and the halogen

What is an example of an everyday decomposition reaction?

 

[D4rkfang]

What is an everyday decomposition reaction?

Rust- O2 + Fe --> Fe2O3

2H2S+3O2 -->2SO2+2H2O

Edit: Hmm, in that case:

baking soda + water --> baking soda + CO2 + water (not too sure of the equation)

How many moles of which reactant will be left over after reacting:

1) 6 moles of H2S with 4 moles of O2

2) 0.16 moles of H2S with 0.2 moles of O2

 

[Kimyia]

What is an everyday decomposition reaction?

Rust- O2 + Fe --> Fe2O3

2H2S+3O2 -->2SO2+2H2O

How many moles of which reactant will be left over after reacting:

1) 6 moles of H2S with 4 moles of O2

2) 0.16 moles of H2S with 0.2 moles of O2

I don't think rust is a decomposition reaction.

 

[skillstriker]

Rust is not a decomposition reaction. It's a synthesis reaction (X+Y-->XY)

 

[Merase]

I have no idea how to approach D4rkfang's Q at the moment, so--
What is an example of an everyday decomposition reaction?
Cellular respiration, which involves the decomposition of glucose. C6H12O6(aq) + 6O2(g) ==> 6H2O(l) + 6CO2(g) + ATP (aka adenosine triphosphate)

And I just want to say that this thread has been quite helpful! Thanks to OP and to those who've hitherto participated.

=Identify an example for each type of bonding, providing appropriate chemical formulas: (4)

• Covalent Molecular:
• Ionic:
• Covalent Network:
• Metallic:

 

[Kimyia]

I have no idea how to approach D4rkfang's Q at the moment, so--
What is an example of an everyday decomposition reaction?
Cellular respiration, which involves the decomposition of glucose. C6H12O6(aq) + 6O2(g) ==> 6H2O(l) + 6CO2(g) + ATP (aka adenosine triphosphate)

And I just want to say that this thread has been quite helpful! Thanks to OP and to those who've hitherto participated.

(Three chem questions to give this thread a decent bump. For great justice.)
=Justify the use of a concentrated H2SO4 catalyst when converting ethanol to ethene, and dilute H2SO4 for ethene to ethanol. (3)
=A chemical is tested with three indicators, giving a yellow reading for methyl orange, a blue reading for bromothymol blue, and a colourless reading for phenolphthalein. Justify whether the solution is weakly acidic, strongly acidic, neutral, weakly basic, or strongly basic. (5) Bonus: With regards to the aforementioned indicators, name a possible pH range between which the solution pH is found. (1)
=Identify an example of each type of bonding, providing appropriate chemical formulas: (4)

• Covalent Molecular:
• Ionic:
• Covalent Network:
• Metallic:

Aren't these meant to be prelim questions?

 

[nightweaver066]

2012'ers here:
http://community.boredofstudies.org/showthread.php?t=277226&p=5735486

 

[Demento1]

Rust is not a decomposition reaction. It's a synthesis reaction (X+Y-->XY)

Very true. A simple decomposition reaction could be:



Whereby the arrow symbolises electric current passed through.