Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta

Which has a higher boiling point - alkane or alkene? [PLEASE HELP / DISCUSSION] watch

    • Thread Starter
    Offline

    13
    ReputationRep:
    I thought it would be alkanes as there are more electrons available due to 2 more hydrogen bonds, so the London forces would be stronger so more energy is needed to overcome these.

    Any comments?

    Assume the discussion concerns ethane and ethene.
    Offline

    2
    ReputationRep:
    I'm pretty sure I haven't seen such a question before simply because they are both very similar. The 2 extra hydrogen atoms don't do much to help vdw forces because H atoms only have 1 electron each. 2 electrons overall make little to no difference. Therefore, the difference in boiling points would be negligible.
    Offline

    5
    ReputationRep:
    (Original post by nwmyname)
    I thought it would be alkanes as there are more electrons available due to 2 more hydrogen bonds, so the London forces would be stronger so more energy is needed to overcome these.

    Any comments?

    Assume the discussion concerns ethane and ethene.
    I think it's the alkene because it has a double bond so more energy is required to break the pie/ sigma bond?
    Offline

    19
    ReputationRep:
    (Original post by RedRosesBloom)
    I think it's the alkene because it has a double bond so more energy is required to break the pie/ sigma bond?
    How does a boiling point have anything to do with covalent bonds? And it's pi, or π. Not pie.
    Offline

    5
    ReputationRep:
    (Original post by alow)
    How does a boiling point have anything to do with covalent bonds? And it's pi, or π. Not pie.
    Ok Mr. Sherlock. I said 'i think' not 'this is the right answer'.
    • Thread Starter
    Offline

    13
    ReputationRep:
    (Original post by rosemondtan)
    I'm pretty sure I haven't seen such a question before simply because they are both very similar. The 2 extra hydrogen atoms don't do much to help vdw forces because H atoms only have 1 electron each. 2 electrons overall make little to no difference. Therefore, the difference in boiling points would be negligible.
    Yes I mean they would be negligible but on smaller margins, the alkane would still have the higher boiling point, right?
    Offline

    17
    ReputationRep:
    (Original post by alow)
    How does a boiling point have anything to do with covalent bonds? And it's pi, or π. Not pie.
    the enthalpy change in breaking a double bond would be greater than in a single bond
    Offline

    14
    ReputationRep:
    (Original post by RedRosesBloom)
    Ok Mr. Sherlock. I said 'i think' not 'this is the right answer'.
    yeah but it doesn't take a genius to work out that covalent bonds aren't broken when a compound is boiled
    Offline

    5
    ReputationRep:
    (Original post by richpanda)
    yeah but it doesn't take a genius to work out that covalent bonds aren't broken when a compound is boiled
    Yes, I know. Calm down genius, I didn't say it did!
    Offline

    14
    ReputationRep:
    (Original post by RedRosesBloom)
    Yes, I know. Calm down genius, I didn't say it did!
    not...sure...if...serious. You are aware that a pi and sigma bonds are covalent bonds?
    (Original post by RedRosesBloom)
    I think it's the alkene because it has a double bond so more energy is required to break the pie/ sigma bond?
    Offline

    5
    ReputationRep:
    (Original post by richpanda)
    not...sure...if...serious. You are aware that a pi and sigma bonds are covalent bonds?
    YES I'm aware. I meant that I didn't say, it takes a genius to work out that covalent bonds aren't broken when a compound is boiled
    • Community Assistant
    • Very Important Poster
    Offline

    20
    ReputationRep:
    Community Assistant
    Very Important Poster
    The boiling points are very similar but alkenes in general (for the same length of chain) have a boiling point a small number of degrees lower than the corresponding alkane.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: May 26, 2016
Poll
Do you agree with the proposed ban on plastic straws and cotton buds?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.