In examkrackers they clearly say that branching of an alkane results in a lower BP and a higher MP. On SDN a post by QofQuimica states that branching raises both BP and MP. Which one is correct.
In examkrackers they clearly say that branching of an alkane results in a lower BP and a higher MP. On SDN a post by QofQuimica states that branching raises both BP and MP. Which one is correct.
In examkrackers they clearly say that branching of an alkane results in a lower BP and a higher MP. On SDN a post by QofQuimica states that branching raises both BP and MP. Which one is correct.
I think you did a good job of explaining it. A branched alkane will have less surface area on a molecule because the "inner" portions of that molecule are blocked by the branches. A branched molecule will not interact with nearby molecules as a non-branched molecule so there are less forces holding it together so the vapor pressure increases accordingly (BP down).The boiling point of Alkanes depends on the vanderwaals forces. As the surface area increases, so does the boiling point because the adjacent molecules can better interact resulting in greater vanderwaal forces. Due to this reason, straight chains have a greater boiling point than branched chain.
Melting point is a little tricky. Melting point depends on how well a solid is packed into its rigid form. If branching enables the molecule to be arranged in a tightly packed solid form, then the melting point increases. However, if the branching hinders the tight packaging of the molecule, then this would lower the melting point. In other words, branched chain alkanes can have higher or lower melting points depending on the packaging of the molecules into a solid.
Hope that was helpful
Edit: I assumed that the straight chain and branched chain have the same number of carbons.
I think you did a good job of explaining it. A branched alkane will have less surface area on a molecule because the "inner" portions of that molecule are blocked by the branches. A branched molecule will not interact with nearby molecules as a non-branched molecule so there are less forces holding it together so the vapor pressure increases accordingly (BP down).