Chem Questions (1 Viewer)

[Dreamerish*~]

this is a second game (excuse me for my madness)

i think someone else has created a game like this before, but since i'm too lazy to dig it up, i'm starting a new one.

basically, you have to answer a syllabus-related question asked by the previous post. please leave out the options.

Is rainwater acidic, basic or neutral? Explain the formation of normal rainwater of about this pH using an equation of a gas dissolving in water.

 

[wanton-wonton]

What the fuck, is that your way of getting other people's dot points so you don't have to do 'em yourself?

A: rain water is acidic, because there are always a little bit of carbon dioxide dissolved in it.

CO2 + H2O -> H2CO3 (I think.)

I can't believe I'm bloody doing this, I have King Lear to do.

My question: ...... Is acid gay? Syllabus reference 9.2.4

 

[Dreamerish*~]

dude, i've done the whole syllabus

since i keep getting distracted by BoS, might as well...

and you have to ask a question after answering the previous one. but since you didn't i'll do it.

Which chemist said "I can confidently claim that all acids contain oxygen - the acid producer. The property of acidity is due to an acid's composition"?

 

[wanton-wonton]

dude, i've done the whole syllabus

since i keep getting distracted by BoS, might as well...

and you have to ask a question after answering the previous one. but since you didn't i'll do it.

Which chemist said "I can confidently claim that all acids contain oxygen - the acid producer. The property of acidity is due to an acid's composition"?

I did, retard.

A: rain water is acidic, because there are always a little bit of carbon dioxide dissolved in it.

CO2 + H2O -> H2CO3 (I think.)

And for your question...From the top of my head, Lavoiser is the only name I remember?? However you spell that stupid name.

 

[xiao1985]

@ wanton wonton: she's saying u didn't ask a question, not u dind't answer the question retard...

as for u question, acid is very gay indeed:
9.2.4: Oxidation reduction reactions are increasingly important as a source of energy

 

[Jumbo Cactuar]

I did, retard.

A: rain water is acidic, because there are always a little bit of carbon dioxide dissolved in it.

CO2 + H2O -> H2CO3 (I think.)

Hmmm, that answer is pretty retarded!

Carbon dioxide has a solubility of 1.8g/L in water.

Carbon dioxide is leached out of the atmosphere by rain water.

Carbon dioxide is a diprotic acid (pK_a1=6.35, pK_a2=10.33).

CO_2(aq) + H₂O <=> H⁺ + HCO₃^- pK_a1=6.35
HCO₃^- <=> H⁺ + CO₃^2- pK_a2=10.33

 

[Jumbo Cactuar]

Oh and a question! 9.4.3! And challenging this time!

AAS is an amazingly easy test with great selectivity.
- what is AAS used for?
- what is the fundamental relation of quantitative spectroscopy?
- account for the selectivity of AAS.
- how does AAS chemically differ from a flame test?

PS: 1, 2 & 4 are one liners and rep is on the line for first 100% answer!

 

[xiao1985]

lolz so tempted to answer...
wut does q2 mean, don't quite get the q...

 

[funking_you]

Q2 hint: beer's law ..... not hsc syllabus, but i think it should be. VERY SIMPLE yet powerful relationship.

 

[Emma-Jayde]

-AAS is used to detect concentrations of and element in a sample of solution

-Chemically different from a flame test because light intenstity is measured, not flame colour

I'm not entirely sure what you mean by questions 2 and 3.

 

[Jumbo Cactuar]

-AAS is used to detect concentrations of and element in a sample of solution

-Chemically different from a flame test because light intenstity is measured, not flame colour

I'm not entirely sure what you mean by questions 2 and 3.

Emma-Jayde
1 - correct
4 - on the right track - thats how it is methodically different.



nice start!

 

[xiao1985]

AIYA!!! can't it no longer:
q4: aas is absorption, flame test is emission... ><

am i right am i right?!
*eagerly awaits...~~

@chemcoach: awww beer's law... but not required by the syllabus tho..
OMG i can't believe i forgot abt that... jsut got examined last monday

 

[thunderdax]

Does 3 mean the reason we use different colours for each ion?
This is because of the difference of energy that can be absorbed by each metal ion. Since energy that can be absorbed by an ion is quantised (electrons can move between two shells, but not part way in between) there is only one specific frequency of light (and therefore quantity of energy) that will be absorbed by one ion. For this reason we need to be selective when using AAS.

And with 4, a flame test excites an electron to release energy and show a light while AAS makes the electron absorb energy from the light and therefore decrease luminousity.

 

[Jumbo Cactuar]

@ xiao1985 & thunderdax ~ yes you are both correct! It is selective because other species are all atomised/ionised and energy is quantised so there is a very low probability of interference (since there is a limited number of elements). The lamp is constructed from the analyte to ensure the correct wavelength is emitted. Since there is no interference there is a great degree of certainty in the accuracy of the readings - hence it is very selective.

Nobody has actually answered 2 yet! The amount of something something is related to the something of analyte...

 

[Emma-Jayde]

Does it have something to do with electrons exisiting in particular energy levels? Electrons can move from one energy level to another by absorbing electromagnetic radiation of particular frequency. Every element absorbs or emits radiation of a specific frequency that is characteristic of that element. This allows individual elements to be analysed even in the presence of other elements

Or am I completely on the wrong track here?

 

[Jumbo Cactuar]

Question two is sooo amazingly basic! The other questions have been answered.

 

[Budz]

dude, i've done the whole syllabus

since i keep getting distracted by BoS, might as well...

and you have to ask a question after answering the previous one. but since you didn't i'll do it.

Which chemist said "I can confidently claim that all acids contain oxygen - the acid producer. The property of acidity is due to an acid's composition"?

Dont know if anyone answered this yet however i believe it was Lavoiser who said that

 

[lfc_reds2003]

to jumbo cactars q number 2

i think:

absorbance is proportional to the concentration of light-absorbing molecules in the sample.

 

[Budz]

Another Question... although boring

25M of HCl reacts completly with 0.2M 20mL of Ba(oh)2
What is the initial Volume of HCl

 

[xiao1985]

@ jumbo: still not entirely sure abt the question... but is the answer logrithmic?!