monounsaturated vs polyunsaturated

[liv]

is there a formula for figuring these out just from their molecular formula? eg. linolenic acid (and yes i could google it but what if they give you sth on the exam you can't google?)
 because i can't figure it out still. and someone told that there is a formula that you apply to see if something is monounsaturated or polyunsaturated, but i can't find it anywhere.

help?

[naved_s9994]

is there a formula for figuring these out just from their molecular formula? eg. linolenic acid (and yes i could google it but what if they give you sth on the exam you can't google?)
 because i can't figure it out still. and someone told that there is a formula that you apply to see if something is monounsaturated or polyunsaturated, but i can't find it anywhere.

help?

Just work it out from the amount of Double bonds..

[naved_s9994]

^ I mean number of

[vexx]

is there a formula for figuring these out just from their molecular formula? eg. linolenic acid (and yes i could google it but what if they give you sth on the exam you can't google?)
 because i can't figure it out still. and someone told that there is a formula that you apply to see if something is monounsaturated or polyunsaturated, but i can't find it anywhere.

help?

yeah i just use a rule that we use in muep chem,
no. of double bonds or rings = number of carbons - (no. of hydrogens/2) + 1
and note that the number you get includes the c=o bond from the carboxyl group.

[superflya]

rewrite them in the form u find it in the data book e.g linoleic C17H31COOH

general formula for saturated would be CnH2n+1
for linoleic it is C2n-3      difference of 4 H, each carbon double bond accounts for 2 H, so u know theres 2 carbon double bonds.

[liv]

oh oh oh

thankies all!

[chansthename]

^ I mean number of

there is an edit button at the top right corner of your post.

yeah i just use a rule that we use in muep chem,
no. of double bonds or rings = number of carbons - (no. of hydrogens/2) + 1
and note that the number you get includes the c=o bond from the carboxyl group.

nice, (i'm gonna spend all night testing it)

[naved_s9994]

is there a formula for figuring these out just from their molecular formula? eg. linolenic acid (and yes i could google it but what if they give you sth on the exam you can't google?)
 because i can't figure it out still. and someone told that there is a formula that you apply to see if something is monounsaturated or polyunsaturated, but i can't find it anywhere.

help?

yeah i just use a rule that we use in muep chem,
no. of double bonds or rings = number of carbons - (no. of hydrogens/2) + 1
and note that the number you get includes the c=o bond from the carboxyl group.

Isnt that the Double Bond Index formula?

[vexx]

^ edit, naved nahh it's called something else as it includes number of rings, something about hydration index (no idea just guessing haha)

^ I mean number of

there is an edit button at the top right corner of your post.

yeah i just use a rule that we use in muep chem,
no. of double bonds or rings = number of carbons - (no. of hydrogens/2) + 1
and note that the number you get includes the c=o bond from the carboxyl group.

nice, (i'm gonna spend all night testing it)

haha yeah it works well, all those questions are done so much quicker through that xD

[Martoman]

is there a formula for figuring these out just from their molecular formula? eg. linolenic acid (and yes i could google it but what if they give you sth on the exam you can't google?)
 because i can't figure it out still. and someone told that there is a formula that you apply to see if something is monounsaturated or polyunsaturated, but i can't find it anywhere.

help?

yeah i just use a rule that we use in muep chem,
no. of double bonds or rings = number of carbons - (no. of hydrogens/2) + 1
and note that the number you get includes the c=o bond from the carboxyl group.


Or alternatively... just get rid of the +1 as this isn't what we want.