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isomers- molecular formula

how can I find out the molecular formula of the two isomers formed after reacting butane with chlorine? The isomers had a molar mass of 92.5g mol-1.

Thank in advance.. :smile:

Reply 1

CJ Makani

The free radical can form on two positions on the hydrocarbon, either at the end of the molecule (on one of two methyl groups) or on one of the two central carbon atoms in butane, then a chlorine can be taken from a Cl₂ molecule.

Post what you think the answer is.

Reply 2

pure_joy

there are two possible answers. as mentioned above, it depends on where chlorine binds to butane:
1) CH2Cl-CH2-CH2-CH3 1-chlorobutane
2) CH3-CHCl-CH2-CH3 2-chlorobutane

it's important, that for example CH3-CH2-CHCl-CH3 isn't 3-chlorobutane, but 2-chlorobutane. you can count the carbon atoms from each side, depending on where the number of chlorine will be smaller.

Reply 3

n0b0dy

thanks for your help but im quite lost..

this is the full question:

The major hydrocarbon in camping gas is butane. Some camping gas was reacted with chlorine to form a mixture of isomers.
i) what conditions are required for this reaction to take place? for this i have ultra-violet light as the answer, not sure if there is anything else..

ii) two isomers, A and B were separated from this mixture. these isomers had a molar mass of 92.5g per mole.deduce the molecular formula of these two isomers.

im not sure where the structure of the molecule comes into this, can anyone explain? :s-smilie:

thanks a lot.. :smile:

Reply 4

Eau

well isomers, at least structural isomers are compounds with the same molecular formula but different structure formulae.

Reply 5

pure_joy

i) what conditions are required for this reaction to take place? for this i have ultra-violet light as the answer, not sure if there is anything else..

ii) two isomers, A and B were separated from this mixture. these isomers had a molar mass of 92.5g per mole.deduce the molecular formula of these two isomers.

light is the right answer for point 1- it's the condition needed for free radical substitution of alcanes

Celeritas has already explained what structural isomers are. So the two isomers will have the same molecular mass and will only have a different location of the chlorine atom. There can't be any difference in the hydrocarbon chain, (i.e. CH3-C(CH3)Cl-CH3 has the same mass, but it's not formed in a reaction of Cl2 with butane), so there are only two answers.

Reply 6

subhastar

wait i dont get it. why have they given the molar mass and so wen do u use that even? the answer i got was C4H9Cl nd i know thats wrong but i still dont this question.

Reply 7

alow

Original post by subhastar

wait i dont get it. why have they given the molar mass and so wen do u use that even? the answer i got was C4H9Cl nd i know thats wrong but i still dont this question.

This thread is close to 10 years old.

Reply 8

subhastar

loool wow. i was doing the same exact question from my textbook nd was trynna look for answer so dis website had it apparently.
but i no my answer is right now anyway...
yayy