Predictions for Chemistry 2014 HSC? (7 Viewers)

[enigma_1]

so many users but no-one's saying anything?



Speak people!

 

[seventhroot]

so many users but no-one's saying anything?



Speak people!

hi

 

[SuchSmallHands]

Why do you know so much random information T_T You make me doubt myself. Further example in your response:

"Satellite based instruments can be used to detect ozone concentration in the stratosphere. Following calibration issues with the last Total Ozone Mapping Spectrometer (TOMS) unit in orbit, they were replaced in 2007 by the Ozone Mapping Instrument operated from the NASA Aura. Satellite based instruments map differences in incoming solar energy and backscattered UV light across earth. In doing so, these instruments highlight areas if weakness in the ozone layer by noting the failure of the ozone layer to absorb UV light.
The Donson Ozone Spectrophotometer is a ground based izone concentration detection system that is less precise than satellite based models and thus primarily used for corroborating satellite data. It works by measuring the amount if one wavelength of UVA radiation reaching earth, which does not have the energy to photolysise ozone and thus is not absorbed by the ozone layer, against one wavelength of UVB radiation, which does have the energy to photolysise ozone and thus will reach earth in an amount which is directly proportional to ozone concentration in the stratosphere."

Bold: never heard of such things. Am i going to get b5
My understanding is basically Satellite-based TOMS: Measure ozone concentration at various altitudes and geographical locations (no idea how; where did you learn this?), resulting in an ozone concentration map
Ground-based spectrophotometers: In a vertical column, measures intensity of a wavelength characteristically absorbed by UV-B and UV-C, which is then compared to a different wavelength to measure total-column ozone in Dobsin units DU

Red: Do you mean inversely proportional?

Ooops yes, thanks for picking up on that! We don't actually have any TOMS in orbit any more, but I'm sure there are plenty of people who don't know that and I'm sure they'd still accept an answer based on TOMS. I'm really into space, even more so when I was younger, I remember when they lost contact with the last TOMS when we in year 5 I think, that's the only reason I knew not to trust my textbook on that one. You really should note that the UVB/UVC has to be compared to a wavelength greater than 310nm (ie. UVA, technically a very small amount of UVB but such an insignificant amount it's not worth mentioning), but other than that your answer for the ground based spectrophotometer would probably get the 2 marks.

 

[enigma_1]

hi

ahaha more people pls

We're all friendly

 

[SuchSmallHands]

Industrial: Describe how the products of electrolysing dilute and concentrated NaCl solution could be identified (4)

I was stuck on this fml (WTF I NEVER LEARNT TO IDENTIFY CL2)

Bubble the evolved gas through water and add AgNO3, a white precipitate which blackens in sunlight indicates the presence of Cl-. (I don't do industrial, that's just from core knowledge, you might need to do something totally different. Can an industrial person please confirm?)

 

[SuchSmallHands]

* unionised water, obviously

 

[iStudent]

 

[enigma_1]

View attachment 31015

uhh idk e?

 

[iStudent]

Nope

 

[QZP]

c?

 

[iStudent]

1.000 ml of 0.1000 mol/L HCl was diluted to 100.0mL with deionized water. 10.00 ml of this solution was diluted to 100.0 ml again using deionized water. What is the pH of the final solution? Show working.

 

[iStudent]

c?

Yes that's correct. Dw about that question. Slightly trespassed boundaries of syllabus.

 

[iStudent]

What is the oxidation state of molybdenum in the ion [Mo2O4(SCN)6] 4-
the numbers in the brackets are supposed to be below. 4- is the total charge

 

[enigma_1]

1.000 ml of 0.1000 mol/L HCl was diluted to 100.0mL with deionized water. 10.00 ml of this solution was diluted to 100.0 ml again using deionized water. What is the pH of the final solution? Show working.

c1v1=c2v2

0.1 x 0.001 = c2 x 0.1

c2 = 0.001mol/L

c2v2 = c3v3

0.001 x 0.01 = c3 x 0.1

c3 = 0.0001mol/L

ph =-log (0.0001) = 4

oh gosh that's so messy, is it even right?

 

[QZP]

1.000 ml of 0.1000 mol/L HCl was diluted to 100.0mL with deionized water. 10.00 ml of this solution was diluted to 100.0 ml again using deionized water. What is the pH of the final solution? Show working.

Is it 4? All done in my head soz edit: just look at dilution factors

What is the oxidation state of molybdenum in the ion [Mo2O4(SCN)6] 4-
the numbers in the brackets are supposed to be below. 4- is the total charge

How was i meant to know the charge of SCN -_-

 

[iStudent]

c1v1=c2v2

0.1 x 0.001 = c2 x 0.1

c2 = 0.001mol/L

c2v2 = c3v3

0.001 x 0.01 = c3 x 0.1

c3 = 0.0001mol/L

ph =-log (0.0001) = 4

oh gosh that's so messy, is it even right?

Yep that's correct

 

[enigma_1]

Yep that's correct

oh cool thanks

 

[enigma_1]

Is it 1? All done in my head soz

How was i meant to know the charge of SCN -_-

brahh write it out

SCN is -1 I think

 

[iStudent]

Is it 1? All done in my head soz

How was i meant to know the charge of SCN -_-

You should know it. SCN is a polyatomic ion you've seen in chem monitoring (the deducing ions prac). It was used in the confirmatory rests for one of the iron ions forgot which one.

 

[QZP]

brahh write it out

SCN is -1 I think

yeah my bad calculated initial pH wrong lol