Which of the molecules can form a hydrogen bond with a water molecule?

1. CH3OH

2. CH2=CHCH3

3. CH3CH2SH

4. CH3OCH3

1 and 4

To determine which of the given molecules can form a hydrogen bond with a water molecule, we need to consider the presence of a hydrogen bond acceptor and a hydrogen bond donor.

A hydrogen bond acceptor is an atom or a group of atoms with a lone pair of electrons that can form a hydrogen bond. In the case of water, the oxygen atom (O) acts as a hydrogen bond acceptor since it has two lone pairs of electrons.

A hydrogen bond donor is an atom that is covalently bonded to a hydrogen atom and can donate its hydrogen atom for hydrogen bond formation. In the case of water, the hydrogen atom (H) attached to the oxygen (O) can act as a hydrogen bond donor.

Now let's analyze each molecule:

1. CH3OH: This molecule has a lone pair of electrons on the oxygen atom, which can act as a hydrogen bond acceptor. It also has a hydrogen atom bonded to the oxygen, making it a potential hydrogen bond donor. Therefore, CH3OH can form a hydrogen bond with a water molecule.

2. CH2=CHCH3: This molecule does not have a hydrogen atom bonded to a highly electronegative atom (such as oxygen or nitrogen), so it cannot act as a hydrogen bond donor. It also does not have a lone pair of electrons on any atom that can act as a hydrogen bond acceptor. Therefore, CH2=CHCH3 cannot form a hydrogen bond with a water molecule.

3. CH3CH2SH: This molecule has a sulfur (S) atom with a lone pair of electrons, which can act as a hydrogen bond acceptor. It also has a hydrogen atom bonded to the sulfur atom that can act as a hydrogen bond donor. Therefore, CH3CH2SH can form a hydrogen bond with a water molecule.

4. CH3OCH3: This molecule has an oxygen atom with two lone pairs of electrons, which can act as a hydrogen bond acceptor. It also has hydrogen atoms bonded to the oxygen, making them potential hydrogen bond donors. Therefore, CH3OCH3 can form a hydrogen bond with a water molecule.

In conclusion, the molecules that can form a hydrogen bond with a water molecule are CH3OH, CH3CH2SH, and CH3OCH3 (options 1, 3, and 4).

To determine which of the given molecules can form a hydrogen bond with a water molecule, we need to consider the presence of hydrogen bonding sites in each molecule.

1. CH3OH (methanol): This molecule contains a hydrogen atom bonded to an oxygen atom. Oxygen is highly electronegative, making the hydrogen atom on methanol partially positive. Hence, CH3OH can form a hydrogen bond with a water molecule.

2. CH2=CHCH3 (propene): This molecule does not have any hydrogen atoms that are directly bonded to highly electronegative atoms like oxygen or nitrogen. Therefore, propene cannot form a hydrogen bond with a water molecule.

3. CH3CH2SH (ethanethiol): Similar to methanol, this molecule contains a hydrogen atom bonded to a sulfur atom. Sulfur is less electronegative than oxygen, but still capable of forming hydrogen bonds with water. Therefore, CH3CH2SH can form a hydrogen bond with a water molecule.

4. CH3OCH3 (dimethyl ether): This molecule has two hydrogen atoms, but they are not directly bonded to electronegative atoms. Instead, the oxygen atom is bonded to two carbon atoms. Therefore, dimethyl ether cannot form a hydrogen bond with a water molecule.

Based on the above analysis, the molecules that can form a hydrogen bond with a water molecule are:

1. CH3OH (methanol)
2. CH3CH2SH (ethanethiol)