Question

1. Based on dipole moments, charges and geometry, explain why H₂O has higher boiling point than CH₃CH₂OH.
2. Compare dipole moments and total energies of cis-2-butene and trans-2 butene. Comment on the similarities or differences in such values and consequences of such in terms of physical and chemical properties.

Answer 1

H2O has high boiling point as compared to CH3CH2OH. Because of the reason that

1. by dipole moment H2O has high dipole moment than ethanol . Thus as the dipole increase tge attraction between their molecules also increases hence b.p of h2o is higher.

2. Similary on the bsis of charge... negative charge on oxygen is high and on hydrogen have high positive charge. in case of ethanol the hydrogen bonding in h2o is present which cause strong intramoleculr force hence b.p is high in cse of h2o.

3. on the bais of geometry in ethanol hydrophobic carbon chain also present which is bulkier than hydrogen in water.

Due to bulky carbon chain repusion occur and lattice can easily breakable. Hence boiling point of h2o is high.

Cis 2 butene and trans 2 butene : In cis 2butene dipole moment is not equal to zero and have net dipole moment.

but in case of trans 2 butene the direction of both ch3 is oppisite to each other and will cancel the direction of diople .

hence net dipole in case of tran 2 butene is zero.

diff. between cis and trans butene..

1. diole moment is zero in trans not in cis.

2. stability in trans is higher than cis.

3. b.p of cis is higher than trans.