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butan-2-one displayed formula, is this right?

Doji

im in doubt with the formula...

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Reply 1

Ancient Beast

Zakz

im in doubt with the formula...

Why have you got CH5 on the left? The carbon can only take 3 hydrogens....

Reply 2

Doji

then howd i fit 10 H's into the structure?

and i thought Carbon can take 4 bonds? so 4 H's ?...but didnt knw how to fit in the 10 H's of butane

Reply 3

Doji

formula CnH2nO

so... C4H8O is butanone...but this is butan-2-one so im confused

Reply 4

JayEm

The formula for butan-2-one is C₄H₈O

2 hydrogens are removed if you make it from butane and replaced with one oxygen through a double bond.

Reply 5

Zoob

butan-2-one = C4H8O not 10H

Reply 6

JayEm

Zakz

formula CnH2nO

so... C4H8O is butanone...but this is butan-2-one so im confused

Butanone is basically the same as butan-2-one, but in the second one, the name tells you where the ketone functional group is.

Reply 7

Ancient Beast

Zakz

then howd i fit 10 H's into the structure?

and i thought Carbon can take 4 bonds? so 4 H's ?...but didnt knw how to fit in the 10 H's of butane

Yes, it does have 4 bonds, but I was saying that specific carbon can only take 3 hydrogens because the other bond is with the second carbon.

Reply 8

Doji

ummmm okay so i knw the formula is now C4H8O ...the -2- just tells me the structure?

any good now?

Reply 9

TheRandomer

I think this is butan-2-one..

with the ketone functional group (double bonded oxygen) coming off the 2nd carbon in the chain.. that's why it's 2-one.. and not just butanone. Got it?
As the person above said, 4 bonds, that includes ANY bonds, not just to the hydrogens... but you will already know that =] but maybe you forgot because you didn't draw it out so you understood where everything went or something.

Reply 10

TheRandomer

Zakz

ummmm okay so i knw the formula is now C4H8O ...the -2- just tells me the structure?

any good now?

Should be CH3 on the left.. and C2H5 on the right methinks. Look on mine where the hydrogens are.

Reply 11

Ancient Beast

Zakz

ummmm okay so i knw the formula is now C4H8O ...the -2- just tells me the structure?

any good now?

Noooo like I said earlier, that left carbon can only take 3 hydrogens because the remaining bond is bonded to the next carbon, so the left one would be CH3.

Reply 12

Ancient Beast

Yeah, punk is correct :yy:

Reply 13

Doji

yeah that displayed formula makes alot of sense, but i thought when your drawing these friggin ketones you need to draw them in the shape i drew them...

Reply 14

Zoob

Beast-man

Noooo like I said earlier, that left carbon can only take 3 hydrogens because the remaining bond is bonded to the next carbon, so the left one would be CH3.

i cant see the pic :s:

Reply 15

JayEm

Zakz

yeah that displayed formula makes alot of sense, but i thought when your drawing these friggin ketones you need to draw them in the shape i drew them...

No, draw then how you like as long as they're correct. :wink:

Reply 16

Doji

Noooo like I said earlier, that left carbon can only take 3 hydrogens because the remaining bond is bonded to the next carbon, so the left one would be CH3.

ohhhhhh, what u mean is, the Carbon has 3 H's bonded to it, and the last bond is the one with the Carbon...i get that now....

just still unsure if im allowed to draw ketones in that way as punk, as the crappy letts study guide shows the ketones in the shape i drew them in.

Reply 17

Doji

JayEm

No, draw then how you like as long as they're correct. :wink:

hehe...ok then lol, thanks alot guys...will rep all the way (giv me some time :biggrin:

)

Reply 18

TheRandomer

Yay I was right =]

Yeah, we've been told we can draw them like that.. or if you think for your course of whatever you can't.. why not draw it the way I have, and then change it?

Reply 19

Ancient Beast

Zakz

just still unsure if im allowed to draw ketones in that way as punk, as the crappy letts study guide shows the ketones in the shape i drew them in.

Punk's way is more correct. Edexcel often, and I suspect most examboards, ask for full structural formulae, thus your way wouldn't get full marks (i.e. once I got marked down for writing -OH in stead of -O-H :rolleyes: