HSC 2017 Chemistry Marathon (1 Viewer)

[dragon658]

Re: HSC Chemistry Marathon 2017

Well yes... but the HSC will be primarily based on the HSC course right?

 

[Simorgh]

Re: HSC Chemistry Marathon 2017

Well yes... but the HSC will be primarily based on the HSC course right?

No it isn't. Its gonna be based on what you did in Year 8....

 

[dragon658]

Re: HSC Chemistry Marathon 2017

Thanks so much! I thought this may be the case.

 

[eyeseeyou]

Re: HSC Chemistry Marathon 2017

please refrain from derailing this thread. If you want to talk about a specific topic or whatever to someone else, please do it via PM or have the conversation somewhere else as we want the marathon running smoothly[/COLOR][/B]

.

 

[mini8658]

Re: HSC Chemistry Marathon 2017

I posted this in the outdated 2k16 thread by accident (-.-'') but what does this mean? I'm really confused by the 'one less/more oxygen than they normally bond to' part.

-ide - elements that react without oxygen
-ite - Elements that reacted with one less oxygen than they normally bond to
-ate - Elements that reacted with the number of oxygen molecules that they normally bond to
-per/ate-Elements that reacted with one additional oxygen molecule than they normally bond to

 

[someth1ng]

Re: HSC Chemistry Marathon 2017

Polylactic acid (PLA) is a thermoplastic polymer that is is derived from renewable resources like corn starch and sugar cane. Most plastics are polymers of nonrenewable petroleum reserves. Plastics derived from biomass (e.g. PLA) are known as “bioplastics”.

PLA is biodegradable and has similar properties to polypropylene (PP), polyethylene (PE), or polystyrene (PS), and its production is compatible with existing industrial equipment used for traditional polymer synthesis. This makes PLA production relatively cost efficient. Accordingly, PLA is the second highest bioplastic produced by volume, only behind thermoplastic starch.

Uses of PLA include plastic films, bottles, and biodegradable medical devices (e.g. screws, pins, rods, and plates that are expected to biodegrade within 6-12 months). For more on medical device prototypes (both biodegradable and permanent) read here. PLA constricts under heat, making it suitable for use as a shrink wrap material. Additionally, the ease with which PLA melts allows for some interesting applications in 3D printing (namely “lost PLA casting” - read more below). In contrast, its low glass transition temperature (include a temperature?) limits its use at high temperature due to deformation.

sourced from: https://www.creativemechanisms.com/blog/learn-about-polylactic-acid-pla-prototypes

I have made some changes so you can see what it might look more like (not complete, but still).

A few points:
1. A lot of changes to be made here, you can definitely improve your writing skills. You need to think about using less words to convey the same information - you use a lot of hand-wavy phrases and have a lot of fluff that adds nothing to your argument. Furthermore, long linking phrases like "on the other hand" make writing more convoluted.
2. If you create an acronym - USE IT.
3. Names of chemicals should not be capitalised unless it is at the start of a sentence. This means "acid" should never be capitalised.
4. Avoid vague phrases like "hot liquid" - try to specify a temperature range. What temperature does PLA become malleable and thus, preventing it from holding liquids at that temp. Another phrase I don't like is "screws, pins, rods, and plates" - are these implants? If so, just say medical implants.
5. Avoid using brackets as much as you can - you really shouldn't ever need full sentences in brackets. It's good to keep it to five words or less within brackets.

Overall, I'd say it's a 2/5 response.

 

[mini8658]

Re: HSC Chemistry Marathon 2017

Reactive Metal + Liquid Water → Metal Hydroxide + Hydrogen Gas
E.g. Na(s) + H2O(l) → NaOH(aq) + H2(g)

^Where does the extra H come from?

 

[jazz519]

Re: HSC Chemistry Marathon 2017

Reactive Metal + Liquid Water → Metal Hydroxide + Hydrogen Gas
E.g. Na(s) + H2O(l) → NaOH(aq) + H2(g)

^Where does the extra H come from?

You haven't balanced the chemical equation. It should be: 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)

 

[mini8658]

Re: HSC Chemistry Marathon 2017

You haven't balanced the chemical equation. It should be: 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)

Thank you

 

[mini8658]

Re: HSC Chemistry Marathon 2017

How many moles of Fe ions, CO ions, C atoms and O atoms are contained in 6 mol of Iron(III) carbonate?

 

[eyeseeyou]

Re: HSC Chemistry Marathon 2017

Assess the use of polystyrene and a named biopolymer in terms of their properties, with references to the statements made in this blog.

Polystyrene is a versatile plastic used to make wide variety of consumer products such as tool handles an plastic furniture. As a hard, solid plastic, it is often used in products that require clarity, such as food packaging and laboratory ware. When combined with various colorants, additives or other plastics, polystyrene is used to make appliances, electronics, automobile parts, toys, gardening pots and equipment and more.

Biopol is a copolymer made up of the monomers PHB (cbbs writing full name) and PHV. The organism used to to synthesise the material is alcaigenes eutrohpus. Since biopol is biodegradable, it only takes 2 years to decompose back into natural components, unlike polyethlyene polyethylene and other petroleum derived plastics; it can be broken down bacteria into carbon dioxide and so will help to reduce levels of rubbish in landfills. It can be made into disposable containers for shampoo, cosmetics, milk bottles (it is non-toxic, insoluble, high tensile strength) and is biocompatible, meaning it is not rejected by the body’s immune system and so can be used safely by many organisms, thus has many medical applications. (ex biocompatible stiches that are left to dissolve/absorbed by the body) hence a renewable resource.

However Biopol is currently very expensive, and currently the demand is not high enough for it to be economically viable. The use of GM bacteria in the production process raises issues of an ethical nature leading to concerns about the effects of GM bacteria on the environment such as if they escape from cultures.

Therefore the use of long-lasting for short lived applications can cause problems for the preservation of living systems in which Biopol is expensive and GM bacteria use to develop it is considered unethical.

 

[eyeseeyou]

Re: HSC Chemistry Marathon 2017

Question: Identify ONE radioisotope used in the fields of medicine AND industry and explain their use in terms of properties. (6 MARKS)


Now please continue this as we need to prep for our half yearlies

 

[Zoinked]

Re: HSC Chemistry Marathon 2017

Question: Identify ONE radioisotope used in the fields of medicine AND industry and explain their use in terms of properties. (6 MARKS)


Now please continue this as we need to prep for our half yearlies

Mate i'll give u a tip. Ask questions that you don't know the answers to. No one enjoys answering the bullshitty rote learning 6-7 markers. For these you just pre-prepare responses and regurgitate in the exam. In the marathon ask questions like calculations or harder 1-4 markers and people will be more inclined to answer, me included.

 

[eyeseeyou]

Re: HSC Chemistry Marathon 2017

Mate i'll give u a tip. Ask questions that you don't know the answers to. No one enjoys answering the bullshitty rote learning 6-7 markers. For these you just pre-prepare responses and regurgitate in the exam. In the marathon ask questions like calculations or harder 1-4 markers and people will be more inclined to answer, me included.

idk if u are trying to insult me....or a serious recommendation....

 

[DatAtarLyfe]

Re: HSC Chemistry Marathon 2017

idk if u are trying to insult me....or a serious recommendation....

Both

 

[Zoinked]

Re: HSC Chemistry Marathon 2017

idk if u are trying to insult me....or a serious recommendation....

Dead serious. I wanna participate but fuck me you ask boring questions. We don't pick chemistry because we like fluffy 6-7 markers.

 

[Mathew587]

can someone explain how oxidation states are used to identify which reaction is undergoing oxidation and reduction?

 

[Commando007]

an increase in oxidation state --> the substance is oxidised (0 to +2)
a decrease in oxidation state --> the substance is reduced (+1 to 0)

if you have 0 to +2, this shows an increase in positivity (decrease in negativity i.e. lost electrons hence oxidation)

 

[Mathew587]

an increase in oxidation state --> the substance is oxidised (0 to +2)
a decrease in oxidation state --> the substance is reduced (+1 to 0)

if you have 0 to +2, this shows an increase in positivity (decrease in negativity i.e. lost electrons hence oxidation)

lmao thanks. it's been a while though haha

 

[Commando007]

lmao thanks. it's been a while though haha

haha true
i didint really notice this thread since a while