Double bond boiling point

[510586]

Do double bonds affect boiling point? I thought they were more stable so they would have a higher boiling point.

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[Lnguyen7]

Yes, double bond affect mp, bp. Examples are saturated fat (animal) and unsaturated (plant). Animal fat is solid and plant fat is liquid at room temperature.

 

[510586]

I think that analogy is more for boiling point. So in a DAT question of the day, C22H46 had a higher boiling point than an alkene. How would we know at what point large alkanes beat double bonds? I think BP is for intermolecular forces in this case? no idea

 

[100%permwinner]

The comparison would be more reasonable if molecules have same or similar number of carbon atoms, as in the case of fatty acids. Molecules with higher boiling points have more intermolecular forces and more energy is required to overcome these interactions. Saturated fats are similar to alkanes (degree of unsaturation is zero) so they pack together nicely and dispersion among the molecules is collectively strong. Unsaturated fats have alkene kinks that prevent orderly packing of these molecules so the dispersion forces as a whole are not as strong as those of saturated fats. Lnguyen7 brings up a good comparison and this argument should explain it.

This link should also be relevant. https://answers.yahoo.com/question/index?qid=20101003034615AAQQHOA

 

[510586]

The comparison would be more reasonable if molecules have same or similar number of carbon atoms, as in the case of fatty acids. Molecules with higher boiling points have more intermolecular forces and more energy is required to overcome these interactions. Saturated fats are similar to alkanes (degree of unsaturation is zero) so they pack together nicely and dispersion among the molecules is collectively strong. Unsaturated fats have alkene kinks that prevent orderly packing of these molecules so the dispersion forces as a whole are not as strong as those of saturated fats. Lnguyen7 brings up a good comparison and this argument should explain it.

This link should also be relevant. https://answers.yahoo.com/question/index?qid=20101003034615AAQQHOA

Oh ok so this question is asking moreso the intermolecular forces (like CH3F higher bp than CH3Cl because of intermolecular hbonds) right? Shoot I got confused and thought since double bonds are stronger bonds it takes more heat or energy to break them. I think bp and mp are almost solely for intermolecular forces with network covalents and ionics being the only intramolecular stuff taken into account, correct?

 

[DAT Destroyer]

Do double bonds affect boiling point? I thought they were more stable so they would have a higher boiling point.

If you consider an unsaturated fatty acid, it will have a lower boiling point. Cis double bonds prevent the tight packing between the hydrocarbon chain, thus lowering intermolecular attractions. This decreases boiling point.

Hope this helps.

 

[510586]

If you consider an unsaturated fatty acid, it will have a lower boiling point. Cis double bonds prevent the tight packing between the hydrocarbon chain, thus lowering intermolecular attractions. This decreases boiling point.

Hope this helps.

Yes it does thank you

 

[510586]

If you consider an unsaturated fatty acid, it will have a lower boiling point. Cis double bonds prevent the tight packing between the hydrocarbon chain, thus lowering intermolecular attractions. This decreases boiling point.

Hope this helps.

Dr Romano would we consider this a fatty acid though? If it is an alkane doesn't branching increase the MP not straight?

 

[510586]

If you consider an unsaturated fatty acid, it will have a lower boiling point. Cis double bonds prevent the tight packing between the hydrocarbon chain, thus lowering intermolecular attractions. This decreases boiling point.

Hope this helps.

Doesn't branching increase MP of hydrocarbons? Can we use the fatty acid rule when dealing with this??