Login

Welcome, Guest. Please login or register.

March 29, 2024, 05:09:15 am

Author Topic: HSC Chemistry Question Thread  (Read 1040610 times)  Share 

0 Members and 2 Guests are viewing this topic.

Sharms

  • Fresh Poster
  • *
  • Posts: 2
  • Respect: 0
  • School: Marist
  • School Grad Year: 2016
Re: Chemistry Question Thread
« Reply #15 on: February 07, 2016, 03:52:24 pm »
0
Just completed the first term of HSC and got 45% in my chem exam, how hard would it be to to change into senior science having missed the whole first term and quickly approaching the half yearlies?
I am dedicated towards learning its just I never really go on with chemistry and all the concepts

jakesilove

  • HSC Lecturer
  • Honorary Moderator
  • Part of the furniture
  • *******
  • Posts: 1941
  • "Synergising your ATAR potential"
  • Respect: +196
Re: Chemistry Question Thread
« Reply #16 on: February 07, 2016, 04:02:56 pm »
0
Just completed the first term of HSC and got 45% in my chem exam, how hard would it be to to change into senior science having missed the whole first term and quickly approaching the half yearlies?
I am dedicated towards learning its just I never really go on with chemistry and all the concepts

Hey Sharms!

I'm sorry to say that I actually don't know anything about Senior Science, in terms of difficulty or anything else. Really the only thing I can recommend is talking to your respective teacher about changing subjects.

Sorry that I can't be of more help! Maybe someone else on the forum has more information :)

Jake
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
English Advanced: 95
Mathematics: 96
Mathematics Extension 1: 98

Studying a combined Advanced Science/Law degree at UNSW

wesadora

  • Forum Regular
  • **
  • Posts: 88
  • School: Arden
  • Respect: 0
Re: Chemistry Question Thread
« Reply #17 on: February 07, 2016, 04:19:07 pm »
0
thanks jake!! :D
Subjects: 3U Maths, Adv. English, Chemistry, Geography, PDHPE

kathywong

  • Guest
Re: Chemistry Question Thread
« Reply #18 on: February 09, 2016, 12:52:19 am »
+1
Hi, what are some chemical properties of radioisotopes? The syllabus dot point says "explain their use in terms of their properties".
My teacher said that "half life and the type of radiation they emit are not chemical properties so im kinda lost. Please help thanks

jakesilove

  • HSC Lecturer
  • Honorary Moderator
  • Part of the furniture
  • *******
  • Posts: 1941
  • "Synergising your ATAR potential"
  • Respect: +196
Re: Chemistry Question Thread
« Reply #19 on: February 09, 2016, 09:33:34 am »
+3
Hi, what are some chemical properties of radioisotopes? The syllabus dot point says "explain their use in terms of their properties".
My teacher said that "half life and the type of radiation they emit are not chemical properties so im kinda lost. Please help thanks

Hey Kathy!

In this case I would respectfully disagree with your teacher. Half life and type of radiation they emit is certainly a chemical property, two of which you should ALWAYS include in any band 6 response. To repeat; they are chemical properties!.

However, there are definitely more chemical properties you can discuss if you want to achieve top marks. Things like state (for Medicine, useful if the compound is a liquid etc.) and ability to latch onto certain compounds in the body (such as Glucose) so that you can track its movement and thereby detect various diseases and illnesses.

The main this to get out of this is that your teacher is wrong. If they want you to include even more, then definitely do, but in the HSC half life and type of radiation is definitely a chemical property.

I hope this helps! Absolutely great question, because often your teachers can be slightly misguided in their approach to the syllabus.

Jake :)
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
English Advanced: 95
Mathematics: 96
Mathematics Extension 1: 98

Studying a combined Advanced Science/Law degree at UNSW

g98

  • Adventurer
  • *
  • Posts: 18
  • Respect: 0
  • School: St Francis de Sales College
  • School Grad Year: 2016
Re: Chemistry Question Thread
« Reply #20 on: February 09, 2016, 06:54:34 pm »
0
Hey Jake!
I have a quick question about studying in general:
What is your opinion on music while you study?

And your lectures in Sydney were great by the way!
Thank you!

jakesilove

  • HSC Lecturer
  • Honorary Moderator
  • Part of the furniture
  • *******
  • Posts: 1941
  • "Synergising your ATAR potential"
  • Respect: +196
Re: Chemistry Question Thread
« Reply #21 on: February 09, 2016, 06:58:48 pm »
+3
Hey Jake!
I have a quick question about studying in general:
What is your opinion on music while you study?

And your lectures in Sydney were great by the way!
Thank you!

Hey g98!

Great question! Actually, the second time I've been asked that today oddly enough.

Throughout my HSC year, I literally listened to Music non-stop. Like seriously, if there wasn't music coming out of my room, I was probably asleep. I didn't feel distracted by it, and it helped time go more,,, manageable?

Once, I tried listening to Classical music and to be completely honest, it actually helped a lot! Still, I found it heaps boring so decided to revert back to Alt-J.

My overall recommendation is just to do whatever you feel comfortable with. If music distracts you, keep it off. If it helps you pass the time, blast it out the windows. There's no "set rule" or particular method that will help you study better.

I know this isn't a very specific answer, but I hope it helps! Great question by the way.

Jake
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
English Advanced: 95
Mathematics: 96
Mathematics Extension 1: 98

Studying a combined Advanced Science/Law degree at UNSW

Happy Physics Land

  • ATAR Notes Legend
  • Forum Obsessive
  • ***
  • Posts: 335
  • MAXIMISE your marks by MINIMISING your errors
  • Respect: +38
Re: Chemistry Question Thread
« Reply #22 on: February 09, 2016, 07:10:53 pm »
+3
Hey Jake!
I have a quick question about studying in general:
What is your opinion on music while you study?

And your lectures in Sydney were great by the way!
Thank you!

Actually if you just type up "study concentration music" on youtube, there's a whole list of those and pretty much all of them have a brain stimulation effect that would help you to concentrate. My recommendation is to turn it to a volume where you can still hear someone calling you but loud enough to cover all the unnecessary noises in the surrounding environment.
Mathematics: 96
Maths Extension 2: 93
Maths Extension 1: 97
English Advanced: 92
Physics: 95
Chemistry: 92
Engineering Studies: 90
Studies of Religion I: 98

2017 ATAR: 99.70
University of Sydney Civil Engineering and Commerce
University of Sydney Faculty of Civil Engineering Scholar
Student Representatives Council Student Housing Officer
City of Sydney Council Sydney Ambassador
University of Sydney Business School Student Mentor
Entrepreneur, Company of Year Junior Achievements Australia

zoe.mckeon

  • Fresh Poster
  • *
  • Posts: 1
  • Respect: 0
  • School: St Mary's College, Gunnedah
  • School Grad Year: 2016
Re: Chemistry Question Thread
« Reply #23 on: February 10, 2016, 07:07:11 pm »
+1
Hey Jake,

I'm just wondering what you found to be an effective study method for Chemistry? I found during Year 11 that I did study but I could not remember much when in an exam, and what I did know was hard to apply to a question....

Thanks for your help.

jakesilove

  • HSC Lecturer
  • Honorary Moderator
  • Part of the furniture
  • *******
  • Posts: 1941
  • "Synergising your ATAR potential"
  • Respect: +196
Re: Chemistry Question Thread
« Reply #24 on: February 10, 2016, 09:24:01 pm »
+3
Hey Jake,

I'm just wondering what you found to be an effective study method for Chemistry? I found during Year 11 that I did study but I could not remember much when in an exam, and what I did know was hard to apply to a question....

Thanks for your help.

Hey Zoe!

Fantastic question, and one which I will soon be devoting an entire resource too. Studying is the hardest part of any subject, and making sure that you tailor your study to each subject is absolutely vital.

I totally agree with you though: the hardest part of studying for Chemistry in particular isn't learning the content; rather, it is applying that content to a standard exam question!

My best advice is to DO PAST PAPERS and COMPLETE PAST QUESTIONS. When you finish a topic, don't just take notes, learn the content etc. Find past questions relating to the topic, answer them, mark them yourself (using marking guidelines), re answer the question so that it's perfect, and then include that answer in your notes.

I would say that, until you've done the above, you haven't actually finished a topic. Don't wait until you finish an entire block of the syllabus (eg. The Acidic Environment etc.); as soon as you finish a dot point or two, try answering questions.

Once you done this enough, you'll know exactly what each question is asking. It's all about interpreting what the markers want, and the only way to do that is to do enough past papers to know exactly what's going on.

To summarise

-     Write notes
-     Learn the content
-     Do past paper questions relating to the topic
-     Mark question
-     Perfect answer
-     Include answer in your notes

I really hope that this helps! Great question, and great to see the activity on this forum! Looking forward to more great questions, and answers from the community!

Jake :)
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
English Advanced: 95
Mathematics: 96
Mathematics Extension 1: 98

Studying a combined Advanced Science/Law degree at UNSW

thushan

  • ATAR Notes Lecturer
  • Honorary Moderator
  • ATAR Notes Legend
  • *******
  • Posts: 4959
  • Respect: +626
Re: Chemistry Question Thread
« Reply #25 on: February 11, 2016, 09:00:16 am »
+3
You'll find you remember content much more easily if you use what you know - whether it be solving stoichiometric problems or synthesising your understanding of the material in more worded and extended response questions.
Managing Director  and Senior Content Developer - Decode Publishing (2020+)
http://www.decodeguides.com.au

Basic Physician Trainee - Monash Health (2019-)
Medical Intern - Alfred Hospital (2018)
MBBS (Hons.) - Monash Uni
BMedSci (Hons.) - Monash Uni

Former ATARNotes Lecturer for Chemistry, Biology

kathywong

  • Guest
Re: Chemistry Question Thread
« Reply #26 on: February 11, 2016, 08:13:28 pm »
0
My questions:
-are transuranic elements and radioisotopes produced in exactly same way ie.using nuclear reactor and particle accelerator?
-Is it not necessary for nuclear fission to occur in nuclear reactor and nuclear fusion to occur in particle accelerator ?
-Will knowing the location discovered and how it is produced for recent discoveries of elements be enough?


I have an assessment coming up so would you mind checking if my notes are correct and if the main important details are mentioned? thank you

Describe how transuranic elements are produced

Neutron bombardment:
- Natural elements are immersed in a nuclear reactor and bombarded with neutrons (or other particles) to produce higher elements as nuclear fission occurs
   
Particle accelerator
-transuranic element atomic number>96 are made by bombarding heavy nucleus with high speed small positive nucleus (e.g. He, C or Boron) in accelerators, synchrotrons, and cyclotrons.


Describe how commercial radioisotopes are produced

Nuclear reactors
-Bombard target nuclei with slow neutrons produced by fission of uranium-235. The nucleus absorbs neutrons hence producing a neutron-rich radioisotope.
      
Particle accelerators
-A machine uses electric and magnetic fields to accelerate charged particles such as protons, or nuclei (eg.Helium) or ion of other atoms (eg. Hydrogen-2 ions, Helium-3 ions) to collide with target nucleus. Nuclear fusion occurs and neutron-deficient radioisotope is produced.
eg. (nuclear fusion) Fluorine-18 is prepared in a cyclotron by bombarding nitrogen-14 with helium nuclei.

Identify instruments and processes that can be used to detect radiation
-Photographic film- Darkening of photographic film indicated the presence of radioactivity. The darkening is due to formation of silver halide crystals as radiation is absorbed by silver salts in the film.

-Cloud Chamber - device that consists a container of supersaturated vapour of water or alcohol. As radiation travels through the device, it ionises surrounding air molecules which causes vapour molecules to condense onto these ions, to produce visible cloud tracks/ trails.

-Scintillation counter:
       - When certain substances like ZnS absorbed energy from alpha, beta and gamma rays, they emit flashes of light which can be collected and amplified in a photo multiplier. Thus, an electrical pulse can be generated and recorded by a  counter
       -Used to measure the amount of radiation exposed to a person who has taken a body scan 

Geiger-Muller counter
        - Best for detection of alpha and beta radiation but cannot tell difference between alpha and beta particles
   - Consists of a sealed glass/metal tube with inside filled with argon gas and with a thin mica window at one end to allow particles to enter
   - Particles enter ionise gas molecules (e.g. argon), emitting electrons which accelerate towards the positive electrode, and ionising more gas as they proceed in their path and create an electrical pulse
   - GM counter records the electrical pulse and convert it to audible clicks

Medical and radioisotopes uses and chemical properties

Cobalt-60:  (industrial/medical)
Chemical properties:
   Chemically inert
   Gamma emitter
   Long half-life of 5.3 years

Relating uses to chemical properties:
- it is an emitter of gamma rays which can penetrate the materials such as metals, paper, rolled steel and detected on the other side using radioactive film,  therefore can measure thickness of these materials or detect faults in metal casting and cracks in aircraft wings.
-The gamma radiation it emits used to sterilise food eg. Strawberries to minimise spoilage and extend shelf life, and medical supplies such as disposable syringes and bandages. Food on a conveyor belt is gamma irradiated by passing it through a chamber containing a safely shielded Co-60 source.

Benefits
-it is chemically inert therefore has relatively low emission of radiation also limits the potential damage to anyone working with the radioisotope.
-potent gamma emitter  - Gamma rays can easily penetrate hermetically sealed packaging and the contents, killing harmful microbes such as bacteria, viruses and fungi. They have sufficient energy to destroy bacteria but not enough to make food radioactive.
-has a reasonably long half-life of 5.3 years since it is chemically inert hence do not require frequent replacement/do not need to be produced on site and can be readily used to treat cancer patients
-Provides effective treatment of many cancerous tumours in sensitive organs because it releases beta and gamma radiation which can easily penetrate and kills abnormal cells
-Cheaper methods of diagnosis and treatment of medical illnesses and cancer
-Provides non-invasive, convenient diagnostic techniques to trace medical illnesses and problems
-medical sterilisation which is more effective than the use of antiseptics and heat treatment

Concerns
-There are concerns that gamma radiation can destroy vitamin content in food and may lead to the formation of harmful compounds in the food. In addition, workers must be protected from irradiation.
-Continued exposure to radiation can lead to diseases such as tissue damage, tumours, cancer and genetic damage
-Without further research, the long-term effects in irradiation of food, are unknown

Technetium-99m (medical):
Chem properties:
-short half-life of 6 hours   
-emits low energy gamma
-can be attached to a range of biological carriers
-relatively unstable and reactive

Relating chemical prop to uses:
-used as a biological tracer for diagnostic imaging.  It can be attached to biological molecule which will concentrate in the targeted organ such as brain, kidney, bones liver and spleen and injected into the body. Then, it will emit gamma radiation which can easily penetrate and detected in various part of body using a gamma camera (scintigraphy) and pinpoint blood clots, constrictions, heart defects and size and location of cancer growth, etc.
eg. Tc-99m phosphonates is used to diagnose skeletal bone problems

Benefits:
-short half-life of 6 hours which is short enough to minimise the exposure of radiation to patient and long enough to examine metabolic processes occurring in the body
-emits low energy gamma radiation which minimises damage to healthy cells/tissues, but can still be detected in the body by a gamma ray sensitive camera.
-Can be attached to a range of biological carriers which will concentrate in a targeted organ
-relatively reactive, so it can be reacted to form a compound with chemical properties that leads to concentration in the organ of interest such as the heart, liver, lungs or thyroid.
-Can be made on site from molybdenum-99 in a transportable generator – Mo-99 is a product of nuclear fission in a nuclear reactor
-Easy to detect using small quantities
-Provides a range of non-invasive, convenient diagnostic techniques  to trace medical illnesses and problems and patient experiences little or no discomfort during the test
-Cheaper methods of diagnosis and treatment of medical illnesses and cancer
-Scintigraphy can be used to produce real time images of body sections which enables observation from all angles instead of Xrays which are static images

Problems:
-It is produced in a nuclear reactor from Molybdenum which is not as dangerous as Plutonium-241 but usual safeguards are necessary (lead shielding) as long term exposure to any radiation can lead to diseases such as tissue damage, tumours, cancer and genetic damage (which leads to deformities in offspring)

Evaluation:
-Tc-99m may cause damage to tissues, or cancer when it is exposed in long term. However, it can be minimised with proper safeguards and in addition its short half-life and low frequency gamma radiation. More importantly, it can give value information concerning a wide variety of metabolic disorders or cancers without the need for invasive surgery. Therefore, there are more benefits associated with the use of Tc-99m and this makes it the most widely used medical radioisotope.

Americium-241 (industrial)
Chemical properties:
-Emits alpha and gamma radiation
-long half-life of 432.7 years

Relating uses to chem prop: (medical and industrial):
-Used in smoke detectors because it is emits alpha and gamma radiation.
When no smoke is present, the alpha particles ionise nitrogen and oxygen in the air in the detector.
When smoke is present, the smoke absorbs the alpha particles emitted, so the rate of ionisation drops and this sets off the alarm.
-Gamma radiation released from Am-241 can be used for indirect analysis of materials radiography and for quality control in manufacturing fixed gauges eg. It has been used to measure glass thickness to help create flat glass
-Gamma rays also provide diagnosis of thyroid function
-It is recently suggested for use as a denaturing agent in plutonium reactor fuel rods to render the fuel unusable for conversion to nuclear weapons

Benefits:
-Long half-life of 432.7 years so do not need frequent replacement
-Alpha particles do not themselves pose a health hazard – as they are absorbed in a few cm of air or by the detector itself

Problems:
-emits alpha and gamma radiation  which can be a serious health hazard if ingested or inhaled
-Dangerous if swallowed as it would concentrate in the skeleton and continue to emit radiation which could cause some cellular damage
-Production is dangerous as it is made through the decay of plutonium-241 in a nuclear reactor which is a highly radioactive element and emits high energy gamma radiation as it decays. Hence, special precautions must be taken when handling plutonium, otherwise it can cause cancer and death

Evaluation:
-It is necessary as it can save lives by warning inhabitants of fires

Sodium-24 (industrial)
Chemical properties:
-Soluble in water
-Emit beta and gamma radiation
-Half life of 15 hours

Relating uses to chem prop:
-it is soluble in water and and used as a leak detector in damaged underground water, gas and oil pipes as it emits beta and gamma radiation. Minimal radiation is detected if it is from inside a pipe, but if the tracer leaks into the soil large radiation are detected

Benefits:
-emits beta radiation  - it does not pose a major health hazard to living things because the radiation will be absorbed by the pipe itself or by its surrounding/ pipe leaks can be located without having to dig up entire pipeline.
-half-life of 15 hours – lasts long enough to find leaks and short enough so that it does not cause any serious permanent pollution to water bodies
-Non-toxic to humans or animals- although it may form organic compounds and be absorbed into the blood stream, this will not strongly affect the health of humans or animals due factors such as its life span and low intensity emission of gamma radiation

Problems:
-Not a naturally occurring isotope hence relies upon nuclear reactors for production which may cause disastrous consequences if large amount of harmful radiation is accidently released 
-Radiation cause undesirable reactions in living tissue and so can cause tissue damage, cancers and/or genetic damage leading to deformities in offsprings.

Evaluation:
-It is certainly valuable in detecting leakages in industry despite some minor disadvantages which can be minimised/eliminated with strict safety precautions

Strontium-90 (industry)
Chemical prop:
-Half-life of 28 years
-emits B radiation

Uses:
-used in thickness gauges to monitor the thickness of sheet materials. Radiation from the Sr-90 is passed through the material to a detector. The intensity of the radiation detected is an indicator of the thickness of the material.

Benefits:
-Long half-life of 28 years so it can be used for extended periods of time so no need frequent replacement

Problem:
-It is similar to Calcium therefore has tendency to replace calcium and this can lead of leukaemia and bone cancer

Iodine-131 (medical)
Chemical prop:
-Half-life of 8 days
-Can be attached to biological molecule
-Emit Beta radiation

Relating uses to chem prop:
-used in medicine to diagnose and treat thyroid cancers.
-When it is tagged to NaI and injected into bloodstream, it will accumulate in the thyroid gland where it undergoes beta and Gamma decay to kill cancer cells or identify thyroid diseases by detection

Benefits:
-Relatively short half-life of 8 days which is long enough for treatment to be done but not too long such that the patient is exposed to excess radiation.

Describe recent discoveries of elements
Copernicium-227
-half-life of 0.24 milliseconds.
-It was discovered in 9th of February in 1996 at the GSI in Darmstadt Germany
-element was created by firing accelerated zinc-70 nuclei at a target made of lead-208 nuclei in a heavy ion accelerator

jakesilove

  • HSC Lecturer
  • Honorary Moderator
  • Part of the furniture
  • *******
  • Posts: 1941
  • "Synergising your ATAR potential"
  • Respect: +196
Re: Chemistry Question Thread
« Reply #27 on: February 11, 2016, 08:50:47 pm »
+1
My questions:
-are transuranic elements and radioisotopes produced in exactly same way ie.using nuclear reactor and particle accelerator?
-Is it not necessary for nuclear fission to occur in nuclear reactor and nuclear fusion to occur in particle accelerator ?
-Will knowing the location discovered and how it is produced for recent discoveries of elements be enough?


I have an assessment coming up so would you mind checking if my notes are correct and if the main important details are mentioned? thank you

Describe how transuranic elements are produced

Neutron bombardment:
- Natural elements are immersed in a nuclear reactor and bombarded with neutrons (or other particles) to produce higher elements as nuclear fission occurs
   
Particle accelerator
-transuranic element atomic number>96 are made by bombarding heavy nucleus with high speed small positive nucleus (e.g. He, C or Boron) in accelerators, synchrotrons, and cyclotrons.


Describe how commercial radioisotopes are produced

Nuclear reactors
-Bombard target nuclei with slow neutrons produced by fission of uranium-235. The nucleus absorbs neutrons hence producing a neutron-rich radioisotope.
      
Particle accelerators
-A machine uses electric and magnetic fields to accelerate charged particles such as protons, or nuclei (eg.Helium) or ion of other atoms (eg. Hydrogen-2 ions, Helium-3 ions) to collide with target nucleus. Nuclear fusion occurs and neutron-deficient radioisotope is produced.
eg. (nuclear fusion) Fluorine-18 is prepared in a cyclotron by bombarding nitrogen-14 with helium nuclei.

Identify instruments and processes that can be used to detect radiation
-Photographic film- Darkening of photographic film indicated the presence of radioactivity. The darkening is due to formation of silver halide crystals as radiation is absorbed by silver salts in the film.

-Cloud Chamber - device that consists a container of supersaturated vapour of water or alcohol. As radiation travels through the device, it ionises surrounding air molecules which causes vapour molecules to condense onto these ions, to produce visible cloud tracks/ trails.

-Scintillation counter:
       - When certain substances like ZnS absorbed energy from alpha, beta and gamma rays, they emit flashes of light which can be collected and amplified in a photo multiplier. Thus, an electrical pulse can be generated and recenient diagnostic techniques to trace medical
Relating uses to chem prop:
-used in medicine to diagnose and treat thyroid cancers.
-When it is tagged to NaI and injected into bloodstream, it will accumulate in the thyroid gland where it undergoes beta and Gamma decay to kill cancer cells or identify thyroid diseases by detection

Benefits:
-Relatively short half-life of 8 days which is long enough for treatment to be done but not too long such that the patient is exposed to excess radiation.

Describe recent discoveries of elements
Copernicium-227
-half-life of 0.24 milliseconds.
-It was discovered in 9th of February in 1996 at the GSI in Darmstadt Germany
-element was created by firing accelerated zinc-70 nuclei at a target made of lead-208 nuclei in a heavy ion accelerator

Hey Kathy!

They look like great notes. I will tell you for sure though that you have way too much content. There is no way you need to memorise that many radioisotopes, and you can definitely ease up on the specific dates and examples. Still, the content itself is great! Just figure out how many isotopes you actually need (ie. Two for med/Two for industrial) and limit your notes to that so you don't need to do unnecessary study.

The answer to all of your questions at the start of your post is that you really don't need to know the answer to that. Nowhere in the curriculum does it require you to have an in depth understanding of the production of transuranic elements (having a basic understanding of particle accelerators etc. is absolutely enough). Remember you are not supposed to be learning all of Chemistry, just the Chemistry in the curriculum dotpoints.

So my overall tip is that it looks like you're doing a little too much study/note taking. It's great to see that you're enthusiastic, but there's not need to go overboard.

Jake :)
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
English Advanced: 95
Mathematics: 96
Mathematics Extension 1: 98

Studying a combined Advanced Science/Law degree at UNSW

kathywong

  • Guest
Re: Chemistry Question Thread
« Reply #28 on: February 12, 2016, 09:33:26 pm »
0
equilibrium  --->>>  Iron (III) ions (yellow colour) reacts with salicylic acid  C7H6O3(s)  producing  Fe(c7h5o3)(aq)(violet colour)    +   H+ (hydrogen ion)


why does increasing in pressure have no effect ? is it because they're not gas molecules

Why does adding Fe(NO3)3(s)/Na(OH)(s) to solution result more intense violet colour  because it thought adding solid/liquid won't affect concentration unless they're aqueous or gaseous


Happy Physics Land

  • ATAR Notes Legend
  • Forum Obsessive
  • ***
  • Posts: 335
  • MAXIMISE your marks by MINIMISING your errors
  • Respect: +38
Re: Chemistry Question Thread
« Reply #29 on: February 12, 2016, 10:15:10 pm »
+3
equilibrium  --->>>  Iron (III) ions (yellow colour) reacts with salicylic acid  C7H6O3(s)  producing  Fe(c7h5o3)(aq)(violet colour)    +   H+ (hydrogen ion)


why does increasing in pressure have no effect ? is it because they're not gas molecules

Why does adding Fe(NO3)3(s)/Na(OH)(s) to solution result more intense violet colour  because it thought adding solid/liquid won't affect concentration unless they're aqueous or gaseous

Hey Kathy:

What a great question, honestly it just covers so many aspects of Le Chatelier's principle and I would indeed see this as a hard question. I really appreciate that you are actually asking this interesting question!

First I will have to congratulate you on correctly stating that the increase in pressure has no effect on the position of the equilibrium because there are no gas molecules involved in this system. Pressure would only affect gas particles because doesnt matter whether we increase or decrease the volume, the amount of the solid and liquids would always stay constant (after all, if you imagine having a rock in a coke can, the rock is not gonna get larger when you pull open the liquid to decrease the pressure). So you have correctly stated that the increase in pressure has no impact due to a lack of gas molecules involved.

Ok the second question is actually a lot more interesting. when you add Fe(NO3)3 into the solution, it is EXTREMELY CRUCIAL to recall something we've learnt back in year 11 chemistry. YES, DISSOCIATION, THATS WHAT IM TALKING ABOUT. Because Fe(NO3)3 is an ionic substance, it is going to undergo dissociation when added to a solution (because of water), forming Iron (III) ions and NO3- ions. This increase in concentration of iron ions then disturbs the system. According to Le Chatelier's Principle, the equilibrium will shift to right, favouring the product side to minimise this disturbance. Hence more Fe(C7H5O3)(aq) are produced and consequently the solution becomes more intensely violet since the product has a violet colour.

Such an awesome question, thanks for posting this. If you still have any concerns or confusions please dont hesitate to ask! :)

Best Regards
Happy Physics Land
Mathematics: 96
Maths Extension 2: 93
Maths Extension 1: 97
English Advanced: 92
Physics: 95
Chemistry: 92
Engineering Studies: 90
Studies of Religion I: 98

2017 ATAR: 99.70
University of Sydney Civil Engineering and Commerce
University of Sydney Faculty of Civil Engineering Scholar
Student Representatives Council Student Housing Officer
City of Sydney Council Sydney Ambassador
University of Sydney Business School Student Mentor
Entrepreneur, Company of Year Junior Achievements Australia