chems syllabus point (1 Viewer)

[hscishard]

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

Right how do I study this dot point? I can't find the evidence in my textbooks, all I can find is just how we've controlled it and how the concentrations shot up.

Are we going to get the evidence in the exam or...?
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[Extra Ordinary]

just get some atmosphere and put it in a jar, and do the same thing during your hsc test then tape the jars to your paper

 

[hscishard]

get some atmosphere and put it in a jar (Y)
excellent

 

[jamesfirst]

Yeah weird dot point.

According to the notes that other people have made, most of them said that the evidence for these oxides are not consistent as they are soluble in water.

Also the concentration of these oxides did not have a drastic increase as much as carbon dioxides. You are allowed to say that the data recorded previously is not consistent and hence the evidence for these oxides are not clearly observable .... im guessing

 

[hscishard]

Thx
Also thx for bringing up the idea of looking at other peoples notes into my mind

 

[jamesfirst]

no problem

But I doubt they'll ask you anything on this dot point since the acidic oxide itself is a big content and they have loads to ask you about the acidic oxides itself...


since it's assess, I guess you could talk about the for and against on the effect of these acidic oxides


one of the evidences are:

1. Acid rain - pH of the soils, lakes and degradation of buildings
2. Ice core samples - not sure why. read it somewhere... maybe it has something to do with the solubility of these oxides

 

[rawrence]

Okay evidence can be in the form of 2 methods, qualitative and quantitative evidence. Quantitative is concerned with evidence which is actually measured, so trapped gas bubbles in ice cores in Antarctica can show the changes in Nitrogen oxide concentrations since the Industrial revolution (which is really what we're concerned with) and post-era.

Keep in mind however, quantitative measurements are inadequate for Sulfur oxides as they continuously react with water to form acid rain which leads to the next type of evidence, qualitative

This is concerned with observable changes such as the degradation of forests and man made buildings made from marble (limestone, CaCO3).

And to finish that all off, the nitrogen oxide levels have increased 15% in the past 150 years, overtaking that of sulfur oxides. It might be useful to remember.

 

[jamesfirst]

what he said =P

 

[FCB]

But technology and measuring instruments werent around until like the 70's. So you can say that there isnt a whole lot of accurate data. There is nothing wrong in saying that either.

 

[jamesfirst]

But technology and measuring instruments werent around until like the 70's. So you can say that there isnt a whole lot of accurate data. There is nothing wrong in saying that either.

Which enhances my point - "You are allowed to say that the data recorded previously is not consistent and hence the evidence for these oxides are not clearly observable"


good point FCB =)

 

[hscishard]

Cool

Also, in this module do we use that ionisation of water constant? Do we also calculate the pH of alkaline solutions?

 

[jamesfirst]

Yes. The ionisation constant is very important in calculating the pH of a solution.

Yes you do calculate the pH of alkaline solution.


You will also learn to calculate the final pH of a mixture of acid and base solution.


Ionisation constant is given in the data sheet but it's also good to remember that pH + pOH = 14

 

[hscishard]

Right which syllabus dot point(s) is this? Is it after 9.3.3?

 

[jamesfirst]

yes