Unit 3B Chemistry :) How was the exams? Comment here :P

[qstar.inc]

Daaaammmmmmmmnnnn -____-

i wrote impurities. is it correct?

 

[Manasa]

the answer is primary and secondary alcohol .. it isn't an aldehyde bcoz aldehydes don't have OH group, and the sample clearly has an OH group sincce misty fumes were formed when tested with PCl5

aahh!!!!! somethin out there is right!!!! thnxxxx wat was ur answer to the 2 observations with sodium iodide?

 

[aniekan]

aahh!!!!! somethin out there is right!!!! thnxxxx wat was ur answer to the 2 observations with sodium iodide?

Misty fuses form at the top of the flask or whatever apparatus used
Bubble of gas

 

[Manasa]

Misty fuses form at the top of the flask or whatever apparatus used
Bubble of gas

-_- damn it!!!!!!

 

[jtbteddy]

aahh!!!!! somethin out there is right!!!! thnxxxx wat was ur answer to the 2 observations with sodium iodide?

misty fumes, bubbles of gas, purple vapour and black solid

 

[Manasa]

misty fumes, bubbles of gas, purple vapour and black solid

yaaaaaaaaay!!!!!!!!!!!!!!!!!!!!!!!!!! got that right!!

 

[alex]

aahh!!!!! somethin out there is right!!!! thnxxxx wat was ur answer to the 2 observations with sodium iodide?

dark grey solid and purple fumes
I dont think there will be any bubbles/fumes because HI will be not be liberated since the iodide ion is a very good reducing agent so I- is readily oxidised to I2.
There will probably be a yellow solid as well, form the reduction of sulfuric acid to sulfur

 

[Manasa]

dark grey solid and purple fumes
I dont think there will be any bubbles/fumes because HI will be not be liberated since the iodide ion is a very good reducing agent so I- is readily oxidised to I2.
There will probably be a yellow solid as well, form the reduction of sulfuric acid to sulfur

well one of my answers is right lol!

 

[aniekan]

dark grey solid and purple fumes
I dont think there will be any bubbles/fumes because HI will be not be liberated since the iodide ion is a very good reducing agent so I- is readily oxidised to I2.
There will probably be a yellow solid as well, form the reduction of sulfuric acid to sulfur

Don't worry about that _ the first reaction always give off fumes :0 Not all the fumes will be trapped

here is my proof
http://www.chemguide.co.uk/inorganic/group7/halideions.html

 

[Missyyy]

to remove any unreacted Iodine

how many marks was this worth? 2 or 1?

 

[Missyyy]

to prevent any side reactions

this was for 2 marks?

 

[Hailstorm94]

i used 55 too...i hope its correct

nope its 50.. mass of the solution 1g = 1cm3 so its 50.. 5g is excess that isnt counted...

 

[Hailstorm94]

the answer is primary and secondary alcohol .. it isn't an aldehyde bcoz aldehydes don't have OH group, and the sample clearly has an OH group sincce misty fumes were formed when tested with PCl5

i did empiral formula question first.. went back and wrote propan-1-ol and propan-2-ol... hopefully get mark?

 

[aniekan]

nope its 50.. mass of the solution 1g = 1cm3 so its 50.. 5g is excess that isnt counted...

50 is correct *>*

 

[solidfire]

fairly easy but why was sodium thiosulphate used instead of water???

 

[Hailstorm94]

fairly easy but why was sodium thiosulphate used instead of water???

to clean off any iodine.. i wrote neutralise any iodide ion/iodine... :-/

 

[jtbteddy]

i did empiral formula question first.. went back and wrote propan-1-ol and propan-2-ol... hopefully get mark?

yuppp that's right! you'll get the marks for it!

to clean off any iodine.. i wrote neutralise any iodide ion/iodine... :-/

yuppp, i wrote the same

 

[solidfire]

that p with the iodine question i wrote
p + l2=(pl2)3 is that right???

 

[Missyyy]

to clean off any iodine.. i wrote neutralise any iodide ion/iodine... :-/

im just gonna go around asking everyone this lol, bear with me but um.. do you remember how many marks this was worth? Im hoping 1! :/

 

[Missyyy]

that p with the iodine question i wrote
p + l2=(pl2)3 is that right???

according to wikipedia, its
P4 + 6I2 ---> 4PI3