1)Which compound below would be expected to have the highest boiling point?
a) CH3-CH2-CH2-CH2-CH2-CH2-CH3
b) CH3-CH2-CH2-CH2-CH-CH3
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CH3
c) CH3-CH-CH2-CH-CH3
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CH3 CH3
d) CH3
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CH3-CH-C-CH3
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CH3 CH3
Do I use molar mass to determine which is the highest?
You can do the molar mass but won't the molar mass be the same for all of them. They look like 7 carbons to me and if they are saturated I expect all of the molar mass will be the same.
The straight chain one will be the highest b.p. Branching the chain makes the b.p. lower. The more branched the lower the b.p.
Why is it that the straight chain is higher?
Branching decreases the surface area some but the explanation I've always heard is that the "long" chains get intertwined and interfere with "escaping" from the liquid.
ok thank you!!
Determining the boiling point of a compound involves multiple factors, including molecular mass, intermolecular forces, and the compound's structure. While molar mass is one consideration, it is not the sole determinant of boiling point.
The highest boiling point is generally associated with compounds having stronger intermolecular forces, such as hydrogen bonding, dipole-dipole interactions, and London dispersion forces.
To evaluate which compound is expected to have the highest boiling point among the options provided, we should first examine the types of intermolecular forces present.
a) CH3-CH2-CH2-CH2-CH2-CH2-CH3: This compound is a nonpolar alkane, and the only intermolecular force it exhibits is London dispersion forces.
b) CH3-CH2-CH2-CH2-CH-CH3: In this compound, the presence of the oxygen atom suggests the possibility of hydrogen bonding, which is a stronger intermolecular force compared to London dispersion forces.
c) CH3-CH-CH2-CH-CH3: This compound contains two nonpolar alkyl groups connected by a polar functional group (a single bond). Although the polar bond allows for dipole-dipole interactions, the absence of a hydrogen atom connected to a highly electronegative atom (such as oxygen or nitrogen) makes hydrogen bonding unlikely.
d) CH3-CH-C-CH3: Similar to c), this compound contains a polar functional group (a carbonyl group). However, since there are no hydrogen atoms connected to a highly electronegative atom, hydrogen bonding is not expected. Again, only dipole-dipole interactions are possible.
Based on the intermolecular forces present, compound b) has the potential for hydrogen bonding, which is stronger than any other intermolecular forces among the options provided. Hence, compound b) (CH3-CH2-CH2-CH2-CH-CH3) is expected to have the highest boiling point.
In conclusion, while molar mass provides a starting point, a more accurate prediction of boiling point involves analyzing the types of intermolecular forces in a compound.