Question Chain Thread !!!

[insomniac90]

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Originally Posted by liamh16

The Haber process is an exothermic reaction....

hahah i knew it. cbb to look it up though.
thanks for correcting me. =]

[j-3-s-5]

Originally Posted by insomniac90

Q. WHAT IS THE DIFFERENCE BETWEEN AMPHITERIC AND AMPHIPROTIC?

An amphiprotic substance is a substance that can act as both a proton donor and as a proton acceptor. (related to Brosnted-Lowry acid-base definitions)

An ampthoteric substance can react as an acid or a base according to the Arrhenius definitions (when dissolved in water an acid increases concentration of hydrogen ions, and a base increases the concentration of hydroxide ions)

They are are so damn similar its confusing lol. Although my understanding of acids and bases is very amatuer lol.

Q. Explain the formation of acid rain. (Including equations)

[JasonNg1025]

Well since it's the formation on Acid Rain, I won't blab about the original sources of stuff.
Basically, acid rain is formed when sulfur dioxide and oxides of nitrogen are emitted into the atmosphere... they see a cloud and dissolve in it. Firstly, for sulfur dioxide:

SO_{2 (g)} + H₂O _(l) --> H₂SO_{3 (aq)}

...which is sulfurous acid. Also, SO₂ turns into SO₃ with other air impurities acting as the catalyst.

2SO_{2 (g)} + O_{2 (g)} --> 2SO_{3 (g)}

... and this dissolves in water to form the well known sulfuric acid.

SO_{3 (g)} + H₂O _(l) --> H₂SO₄

For the oxides of nitrogen... firstly, say we start from NO.

2NO _(g) + O_{2 (g)} --> 2NO_{2 (g)}

Now this one... I'm not too sure. But what I learnt was:

4NO_{2 (g)} + 2H₂O _(l) + O_{2 (g)} --> 4HNO_{3 (aq)}

And stufffff like that. I may be wrong for some equations, we'll need another opinion.

Question: How are radioisotopes and transuranic elements produced? (I know a little, it's just that... in my knowledge they're a bit too similar.)

EDIT: Ow, I hate typing SUB and /SUB now

[minijumbuk]

Jason, you hate sub /sub?
Look at this thread.
http://community.boredofstudies.org/....php?p=3870425

Took me millions of years to subscript the n's and the 3's and the 2's xD
PS: Are you really 13?

Anyways...

First 3 transuranic elements produced in nuclear reactors by neutron bombardment which causes beta decay, forming an element with 1 more proton than before, thus forming a new element.
The rest are made by bombarding a small atom such as carbon into the nucleus of the uranium. The atomic numbers add up, and a new transuranic element is formed.
This is done in a cyclotron or linear accelerator.

Normal radioisotopes are also produced in nuclear reactors by neutron bombardment.

[JasonNg1025]

Ok, thanks ;D

Err, I saw your post. I thought you found a way out using copy and paste
But it's a little different for me
And yes, I turned 13 last saturday

[BradlovesJesus]

Wowwwww... You did Ext. 1 & 2 Maths when you had just turned 12? That's impressive!
How did you go? I must say though, I would've rathered last years exams to this years!

Anywho, you can choose between the following two questions:

"Analyse the relationship between the position of elements in the Periodic Table, and
the acid–base behaviour of their oxides."

and

"The flow chart shows a series of steps involved in the production of ethyl butanoate.

glucose → mixture containing ethanol → pure ethanol → ethyl butanoate

Describe the chemistry and procedure involved in each of these steps, using diagrams
where appropriate."

That last one was a 7 mark question, but that requires a lot of writing, so just a brief overview will do. I've just never been able to remember that for some reason. =[ And the first one's been giving me strife as well.

[j-3-s-5]

Originally Posted by BradlovesJesus

"Analyse the relationship between the position of elements in the Periodic Table, and
the acid–base behaviour of their oxides."

- Metal oxides are mostly basic
- Non metal oxides are mostly acidic.
- Oxides of the 5 elements close to the borderline between metals and non-metals are amphoteric, that is, they show acid and basic properties.

Yeh kinda simple answer but thats all I could come up with lol.

Describe the design and composition of microscopic membrane filters and explain how they purify water.

[minijumbuk]

Originally Posted by JasonNg1025

Ok, thanks ;D

Err, I saw your post. I thought you found a way out using copy and paste
But it's a little different for me
And yes, I turned 13 last saturday

Wow, you're a prodigy =OOOOO

IQ.....~130?

[SkimDawg]

Microscopic membrane filters can be used to remove fine particles and micro-organisms from water that cannot be removed by the normal treatment.
Membrane filters are made of thin polymer sheets with fixed pore sizes. The commonly used polymers are PVC, polycarbonate, polypropylene, polyester and polysulfone. The polymer sheets are folded or wound around a central, rigid core to form a cartridge that can be replaced as required. Other microfiltration membranes consist of fine hollow capillaries that are housed inside a filtering unit. Here the filtered particles are trapped on the outside of the capillaries and the filtrate passes through the centre of the capillary. Water that is to be filtered is made to flow across the surface of the membranes rather than at right angles to prevent clogging.

The filters can be cleaned by back-flushing. Air is blown from the clean side to dislodge trapped particles which are then washed away by the dirty water on the outside.

Membrane filters are widely used for filtering both drinking water and treated sewage. For drinking water, membrane filters can remove virtually all particles larger than 0.2 nanometres including Giardia and Cryptosporidium. Primary and secondary sewage treatment removes about 90% of BOD and 90% of suspended solids from raw sewage. Membrane filtration is widely used in industry, particularly for beverage preparation (including bottled water).

However, no filters can remove substances that are actually dissolved in the water such as phosphates and nitrates and heavy metal ions.

Copied from other thread lol, now next qu

There are many benefits and problems associated with the use of radioisotopes in industry and medicine. Evaluate the impact on society of the use of radioisotopes in both industry and medicine. In your answer, give examples of specific radioisotopes, making reference to their chemical properties. (7 marks).

[danz90]

Well, the other chain thread doesn't seem to be going good.
Let's make this the official study thread.

You know the drill... answer a question - give a question.

Ok, lets begin:

Explain why monitoring of the reaction vessel used in the Haber process is crucial and discuss the monitoring required.

[SkimDawg]

The Haber process is the process of producing ammonia from gaseous hydrogen and nitrogen.
3H2(g) + N2(g) ----> 2NH3(g)
Because the system can come to equilibrium and is exothermic, conditions need to be monitored and kept at levels that favour the formation of ammonia.
Temperature needs monitoring to maintain it at about 500 degrees C. If it falls below this the reaction rate becomes too low and if it rises above this the equilibrium shifts in reverse and the yield of ammonia drops. A iron oxide catalyst is used to raise the reaction rate at this moderate temperature.
A high pressure of 350 atmospheres is used to optimise the yield of ammonia because its production is accompanied by a decrease in the number of gaseous molecules. Pressure needs monitoring because if it drops, the yield of ammonia will also drop but if rises, the reaction vessel may not withstand the pressure.
The ratio of reactant gases must be monitored to keep it at 3:1 H2, N2 because this is the ratio at which these gases react. If this ratio is not adhered to, excess reactant will slow down the reaction and be costly.
For these reasons, it is extremely important to monitor the conditions used in the Haber process. If any of these conditions change the yield of ammonia will not be optimal.

Not quite what you asked, but something along the lines, a generic response i guess you could say ha.

Next qu:
Describe the process of eutrophication, and assess the suitability of water quality tests used to monitor it. (4 marks)

[danz90]

Originally Posted by SkimDawg

The Haber process is the process of producing ammonia from gaseous hydrogen and nitrogen.
3H2(g) + N2(g) ----> 2NH3(g)
Because the system can come to equilibrium and is exothermic, conditions need to be monitored and kept at levels that favour the formation of ammonia.
Temperature needs monitoring to maintain it at about 500 degrees C. If it falls below this the reaction rate becomes too low and if it rises above this the equilibrium shifts in reverse and the yield of ammonia drops. A iron oxide catalyst is used to raise the reaction rate at this moderate temperature.
A high pressure of 350 atmospheres is used to optimise the yield of ammonia because its production is accompanied by a decrease in the number of gaseous molecules. Pressure needs monitoring because if it drops, the yield of ammonia will also drop but if rises, the reaction vessel may not withstand the pressure.
The ratio of reactant gases must be monitored to keep it at 3:1 H2, N2 because this is the ratio at which these gases react. If this ratio is not adhered to, excess reactant will slow down the reaction and be costly.
For these reasons, it is extremely important to monitor the conditions used in the Haber process. If any of these conditions change the yield of ammonia will not be optimal.

Not quite what you asked, but something along the lines, a generic response i guess you could say ha.

Next qu:
Describe the process of eutrophication, and assess the suitability of water quality tests used to monitor it. (4 marks)

Eutrophication involves the addition of nutrients, such as phosphates and nitrates, to waterways. This leads to the thriving/growth of algal blooms. Subsequently, these algal blooms at the water surface block the penetration of sunlight to photosynthetic aquatic plants in the waterway. This ultimately leads to a drop in [O_{2 (aq)}], which causes the death of aquatic organisms (such as fish). The establishment of anaerobic conditions allows for anaerobic bacteria to thrive and decompose organic matter of dead aquatic organisms. Respiration of anaerobic bacteria produces noxious gases such as CH₄ , NH₃ and H₂S. These gases further degrade the waterway.

Tests used to assess the impact of eutrophication, measure levels of DO (dissolved oxygen), and BOD (biochemical oxygen demand).
DO can be tested via the Chemical winkler method (which is a fairly inaccurate method, due to the multiple chemical procedural steps involved), or using an Oxygen sensor, a much more accurate and suitable method of measuring dissolved oxygen. An oxygen sensor uses an electrolytic sensor, which measures the rate of reduction of O_{2 (aq)} , which is proportional to[O_{2 (aq)}].

BOD can be measured using the Five Day Standard. This involves placing 1L of a water sample in complete darkness, for five days, at 20degrees. The difference in readings of [O_{2 (aq)}] before and after the test period, indicates the BOD.

The BOD five day standard, and Oxygen sensor, used to measure BOD and DO, are very suitable methods of assessing the impact of eutrophication upon water quality.

Next: Perform a first-hand investigation to carry out the fermentation of glucose and monitor mass changes.

[liamh16]

Originally Posted by danz90

Eutrophication involves the addition of nutrients, such as phosphates and nitrates, to waterways. This leads to the thriving/growth of algal blooms. Subsequently, these algal blooms at the water surface block the penetration of sunlight to photosynthetic aquatic plants in the waterway. This ultimately leads to a drop in [O_{2 (aq)}], which causes the death of aquatic organisms (such as fish). The establishment of anaerobic conditions allows for anaerobic bacteria to thrive and decompose organic matter of dead aquatic organisms. Respiration of anaerobic bacteria produces noxious gases such as CH₄ , NH₃ and H₂S. These gases further degrade the waterway.

Tests used to assess the impact of eutrophication, measure levels of DO (dissolved oxygen), and BOD (biochemical oxygen demand).
DO can be tested via the Chemical winkler method (which is a fairly inaccurate method, due to the multiple chemical procedural steps involved), or using an Oxygen sensor, a much more accurate and suitable method of measuring dissolved oxygen. An oxygen sensor uses an electrolytic sensor, which measures the rate of reduction of O_{2 (aq)} , which is proportional to[O_{2 (aq)}].

BOD can be measured using the Five Day Standard. This involves placing 1L of a water sample in complete darkness, for five days, at 20degrees. The difference in readings of [O_{2 (aq)}] before and after the test period, indicates the BOD.

The BOD five day standard, and Oxygen sensor, used to measure BOD and DO, are very suitable methods of assessing the impact of eutrophication upon water quality.

Next: Perform a first-hand investigation to carry out the fermentation of glucose and monitor mass changes.

I don't actually know what you're asking me to do, but i'll just sorta justify/outline the method.

Weigh 1g of yeast onto a square of paper, and add it to a 100mL conical flask.
Measure 200mL glucose solution using a 250mL measuring cylinder, and add the solution into the flask carefully. Insert the stopper and bent glass tube. Dry the outside of the flask with paper towel. Weigh the apparatus on a calibrated set of electronic scales. Record the initial mass of the flask and it's contents. Place the reaction apparatus is a 500mL beaker containing 300mL water. Place this beaker on a hotplate to heat the water to a constant temperature of 35*C. Ensure the temperature of this water bath is kept constant throughout the experiment. This is done to accelerate the fermentation process.
After 30 minutes, carefully remove the conical flask from the beaker and dry the outside with paper towel. Weigh the conical flask and it's contents on the same set of scales used prior, and record the weight. Return the flask to the water bath. Connect the rubber hose to the glass tube connected to the flask, and place the other end of the rubber hose submerged in a 200ml beaker containing 150mL of limewater. Observe the initial colour of the limewater. If the limewater goes milky this means CO2 has been produced by the reaction, thus the reaction is taking place sucessfully. Leave the experiment overnight. The next day, observe the colour changes of the limewater, and dry the conical flask and reweigh it with the same scales used before. Record the mass changed. Repeat the steps with a control containing only glucose.




I think that's alright. Correct me if im wrong.



Assess the evidence which indicates increases in atmospheric concentration of oxides of sulfur and nitrogen.

[friction]

All 3 of those first 3 questions were from the 2003 paper lol.

[JasonNg1025]

Assess the evidence which indicates increases in atmospheric concentration of oxides of sulfur and nitrogen.

1) Decrease in pH of water bodies. As we all know, these gases produce acid rain in the atmosphere, so increased levels of acid rain indicate increases in atmospheric concentrations of oxides of sulfur and nitrogen. Include equations if you want, I'm sick of typing those :P

2) Analysis of air bubbles trapped inside Antarctic ice. Holes are drilled into the ice to check, the deeper down they go, the older it is. Hence, by analysing concentrations in order of depth, trends can be taken. This shows that levels have indeed increased.

I'm pretty sure there was one more, just not coming to mind somehow.

It has been difficult to recognise trends which indicate increases in atmospheric concentrations of these gases. This is because the equipment necessary has only been available since the 1970s, and so clear and long trends have not been taken. Concentrations of these are also very small, being 0.001ppm at highly populated areas.

Err, my question is the one from the other chain thread. Not too sure about that one either.

EDIT: Okey, got it.

"There are many benefits and problems associated with the use of radioisotopes in industry and medicine. Evaluate the impact on society of the use of radioisotopes in both industry and medicine. In your answer, give examples of specific radioisotopes, making reference to their chemical properties. (7 marks)."