Predictions for Chemistry 2014 HSC? (5 Viewers)

[SuchSmallHands]

What is there to say about this DP? :/
• Gather, process and present information to interpret secondary data from AAS measurements and evaluate the effectiveness of this in pollution control

- AAS is useful in determining heavy metal pollution in waterways. It is highly sensitive and can give results in ppb. This sensitivity is important in determining concentrations of heavy metals such as mercury, among the most bioconcentrated and xenobiotic trace metals that pollutes waterways. As mercury is bioconcentrated, even relatively small amounts of it present in water can signal relatively high concentrations of the metal in aquatic organisms which may be biomagnified as the fish is consumed by predators including humans. Where mercury concentrations exceed safe levels, anthropogenic sources of the trace metal (mining, smelting and refining of metals and cement manufacturing, for example) may require more stringent limitations to lower the concentration in nearby waterways. Thus, the sensitivity of AAS renders it highly effective for monitoring trace metal pollution which may require control, as the concentrations of these metals are generally very low.
- AAS is, by contrast, not an effective way of testing for non-metallic pollution. Organic waste cannot be detected by AAS, and the presence of anions, such as chloride, also cannot be detected using AAS. Thus, AAS is limited in its effectiveness in identifying a range of pollutants in our waterways.

I'm hoping specifically referencing mercury and the response made when the concentration is high classes as 'interpreting secondary data', but I'd say that in an exam a question like that would just give you a table/graph of AAS results that you can interpret, and then they'd ask you to answer the second part of that dot point with something similar to what I just wrote

 

[QZP]

Isn't there any other pollution it can detect apart from heavy metal pollution in waterways? I was thinking air samples but not too sure

 

[enigma_1]

Isn't there any other pollution it can detect apart from heavy metal pollution in waterways? I was thinking air samples but not too sure

It detects cations, so any concentration of metals anywhere.

Air samples? No I don't think it does that.
If you need to write an answer, always refer to heavy metals and stuff and trace elements. Anything else is not really necessary nor is it in the syllabus :/

 

[QZP]

Alright thanks guys

 

[faisalabdul16]

Why is AAS better than wet methods?

 

[enigma_1]

Why is AAS better than wet methods?

what do you mean by wet methods?

 

[sabz1996]

what do you mean by wet methods?

Gravimetric and volumetric analysis

 

[faisalabdul16]

what do you mean by wet methods?

heueheuhehuehe got ya

Gravimetric analysis

 

[SuchSmallHands]

Why is AAS better than wet methods?

More sensitive, can detect minute traces of an element in a sample. Also more accurate in determining exact concentrations.

 

[enigma_1]

Gravimetric and volumetric analysis

ohh ok thanks

Why is AAS better than wet methods?

Here are reasons I think why:
- AAs is a sensitive analytical technique - allowing it to accurately measure concentration to ppm and even ppb which wet techniques can't (gravimetric)
- AAS set up is simple once you set it up and to test different cations, the only thing you need to change is the hollow lamp cathode to the metal which you are trying to test whereas for gravimetric you have to keep changing and stuff so its more cumbersome
- AAS is selective and it measures the concentration of the metal present in the lamp, like it's cations only and not any others.
- AAS is simple and inexpensive, rather than Gravimetric which is not really that simple nor accurate (I think I repeated myself woops )
- AAs is reliable because absorption spectrums are unique to each element

 

[sabz1996]

ohh ok thanks




Here are reasons I think why:
- AAs is a sensitive analytical technique - allowing it to accurately measure concentration to ppm and even ppb which wet techniques can't (gravimetric)
- AAS set up is simple once you set it up and to test different cations, the only thing you need to change is the hollow lamp cathode to the metal which you are trying to test whereas for gravimetric you have to keep changing and stuff so its more cumbersome
- AAS is selective and it measures the concentration of the metal present in the lamp, like it's cations only and not any others.
- AAS is simple and inexpensive, rather than Gravimetric which is not really that simple nor accurate (I think I repeated myself woops )
- AAs is reliable because absorption spectrums are unique to each element

Wet methods were also very time consuming.

 

[SuchSmallHands]

It detects cations, so any concentration of metals anywhere.

Air samples? No I don't think it does that.
If you need to write an answer, always refer to heavy metals and stuff and trace elements. Anything else is not really necessary nor is it in the syllabus :/

I actually got a bit curious about the air thing when we did AAS in class. I think I found that you could use AAS, but not FAAS (ie. the type we use interchangeably with AAS). It was called Cold Vapour AAS I think, I don't remember much about it though because it was so removed from the context of the syllabus that I didn't want to go too in depth. When you answer AAS questions I think we just treat AAS as only referring to FASS, just for simplicity's sake, and I don't think that can be used to test air (could be wrong though, I often am).

 

[sabz1996]

Isn't there any other pollution it can detect apart from heavy metal pollution in waterways? I was thinking air samples but not too sure

Not too sure but it can also be used for agriculture to determine if soil is deficient in molybdenum, zinc..etc

 

[enigma_1]

I actually got a bit curious about the air thing when we did AAS in class. I think I found that you could use AAS, but not FAAS (ie. the type we use interchangeably with AAS). It was called Cold Vapour AAS I think, I don't remember much about it though because it was so removed from the context of the syllabus that I didn't want to go too in depth. When you answer AAS questions I think we just treat AAS as only referring to FASS, just for simplicity's sake, and I don't think that can be used to test air (could be wrong though, I often am).

ohh never heard of this :/ Interesting to know though!

 

[faisalabdul16]

SSH always surprises me

 

[tomnomnom696]

Wet methods were also very time consuming.

lol disadvantage of AAS is that its also time consuming as you have to use a different lamp for each sample and obtain a calibration curve every time before testing

 

[faisalabdul16]

lol disadvantage of AAS is that its also time consuming as you have to use a different lamp for each sample and obtain a calibration curve every time before testing

Also true.

Time consuming as a disadvantage is out for both

 

[sabz1996]

lol disadvantage of AAS is that its also time consuming as you have to use a different lamp for each sample and obtain a calibration curve every time before testing

Oh lol, thanks for that.

 

[faisalabdul16]

How did you ensure reliability and validity when conducting the fertilizer experiment?

 

[SuchSmallHands]

ohh never heard of this :/ Interesting to know though!

I may not know half the things on the syllabus, but I know heaps of irrelevant stuff hahaha