Chemistry study thread (1 Viewer)

[HamuTarou]

me justify...u round up the 2.5 -> 3so u get CH3

alkane....yeah, times CH3 by 2 u get C2H6 (methane)

i reckon my test was esay, all my past papers were way harder

 

[mitsui]

a] so let the hydrocarbon be 100g
then mass of C is 82.6g
mass of H is 17.4g

then n(C)=7..
n(H)=17.4

mole ratio: C:H is 1:2.5
so empirical formula is C2H5

so no, i dont it is an alkane.. XD..but mite be wrong, wat u do think?


______________________________________________________________

..oh gr8t.i think my answer is wrong.. XD
how the hell can it be a C2H5??...xD..too many hydrogen for a hydrocarbon. =\

if u wanna realli around the asnwer up..it could be C2H6.

 

[mitsui]

nah if it is C2H6, it is an alkane.. =P
molecular formula C2H6..... >.>...

gr8t..lets pray my test is gonna be easy..but my teacher enjoys giving us hard test
he reckon there is no pt if we all ace it. =|

 

[kazan]

a] so let the hydrocarbon be 100g
then mass of C is 82.6g
mass of H is 17.4g

then n(C)=7..
n(H)=17.4

mole ratio: C:H is 1:2.5
so empirical formula is C2H5

so no, i dont it is an alkane.. XD..but mite be wrong, wat u do think?

what is it? carbon has an unbonded "arm"......
.....h h
.....| |
h--c--c--h
.....|
.....h

can you explain your working out for me? i diddn't understand

someone else put a question up

 

[mitsui]

what is it? carbon has an unbonded "arm"......

h h
| |
h--c--c--h
|
h

can you explain your working out for me? i diddn't understand

someone else put a question up

i dont think C2H5 exists... not in our chemistry level anyway

so betta round 2.5 up to 3

like..HamoTarou? said. lolz

 

[HamuTarou]

yeah.. always round up....

methane (C2H6)
H H
| |
H-C-C-H
| |
H H



ugly diagram =.='

 

[mitsui]

not for chem atm...*thx god!*... but heaps for maths
reckon we should open a 3u thread too. =P

 

[HamuTarou]

methane C2H6...
empirical CH3...

pretty sure now

 

[HamuTarou]

sure..i'll help

 

[kazan]

i dont think C2H5 exists... not in our chemistry level anyway

so betta round 2.5 up to 3

like..HamoTarou? said. lolz

i edited my thing


what is it hay. im keen to find out

whats the next question

 

[kazan]

ok since no one wants to give a question.....

summarise the difference between the boiling and electrolysis of water as an example of the difference between physical and chemical change.

 

[HamuTarou]

ohhh had that one before...

boiling: changing from liquid to gas by breaking the intermolecular forces (hydrogen bonds). there are no changes in the water molecules. this is an example of physical change.

electrolysis: the chemical breaking down of the covalent molecular bonds between the oxygen and hydrogen atoms using electricity. this is an example of chemical change.

 

[Loz_metalhead]

I got C2H5

Am I wrong? You put the percentage over the atomic mass. So therefore it cant be an alkane.

 

[kazan]

if it is c2h5 then carbon has an unbonded "arm" so it cant work

 

[Loz_metalhead]

Yeh you cant just round up...2.5 to 3...you cant do that.

So therefore it cant be an alkane...I dunno.

 

[HamuTarou]

dude, u round up the empirical formula! i got CH2.5...u kow 2.5 cannot exist so u round it up to CH3. this is the empirical formula (simpliest form)
then to fins the structual formula (actual form) u times it by a number (i guessed its two, and it worked) so the structual formula of CH3 is C2H6, an alkane (ethane)

OMG!! i named it wrong all along...should be ethane not methane! srry dudez!

 

[Loz_metalhead]

I got C1 H2.5


You have to times it by 2. So C2H5. Thats how my teacher taught me

EDIT: Just looked at notes and thats exactly how she taught us. In the examples we had like 1 :1.5 so you have to times by 2. Anywayz, maybe she is wrong...

 

[HamuTarou]

Round It Up!!!

 

[ta1g]

another ?- what is gay-lussacs law and what is avagrados law?

 

[Loz_metalhead]

^they will be on our data sheet.