When ethyl alcohol, CH3CH2OH, dissolves in water, how many hydrogen bonds are formed between one ethyl alcohol molecule and surrounding water molecules? Sketch the hydro- gen bonding interactions. (Hint: Add lone pairs of electrons to the structure before drawing hydrogen bonds.)

Verified step by step guidance

1. Step 1: Draw the Lewis structure of ethyl alcohol, CH3CH2OH. Remember to include all the valence electrons and the lone pairs on the oxygen atom.
2. Step 2: Identify the hydrogen bond donors and acceptors in ethyl alcohol. Hydrogen bond donors are the hydrogen atoms attached to highly electronegative atoms (like oxygen), and hydrogen bond acceptors are the electronegative atoms with lone pairs of electrons (like oxygen). In ethyl alcohol, the hydrogen atoms attached to the oxygen atom can act as hydrogen bond donors, and the oxygen atom can act as a hydrogen bond acceptor.
3. Step 3: Draw the Lewis structure of water, H2O. Identify the hydrogen bond donors (the hydrogen atoms) and acceptors (the oxygen atom).
4. Step 4: Now, draw the hydrogen bonds between the ethyl alcohol and water molecules. A hydrogen bond is represented by a dotted line between the hydrogen bond donor (hydrogen atom) and the hydrogen bond acceptor (oxygen atom).
5. Step 5: Count the number of hydrogen bonds formed. Remember, each ethyl alcohol molecule can form two hydrogen bonds with water - one from the hydrogen atom of the -OH group in ethyl alcohol to the oxygen atom in water, and another from the hydrogen atom in water to the oxygen atom in the -OH group of ethyl alcohol.

Key Concepts

Hydrogen Bonding

Hydrogen bonding is a type of intermolecular force that occurs when a hydrogen atom covalently bonded to a highly electronegative atom, such as oxygen or nitrogen, interacts with another electronegative atom. In the case of ethyl alcohol and water, the hydrogen atoms of the hydroxyl group (-OH) in ethyl alcohol can form hydrogen bonds with the oxygen atoms of water molecules, significantly influencing the solubility and properties of the solution.

Molecular Structure of Ethyl Alcohol

Ethyl alcohol (CH3CH2OH) consists of a two-carbon chain with a hydroxyl (-OH) functional group. The presence of the hydroxyl group makes ethyl alcohol polar, allowing it to interact favorably with polar solvents like water. Understanding the molecular structure is crucial for predicting how many hydrogen bonds can form between ethyl alcohol and water.

Lone Pairs of Electrons

Lone pairs of electrons are pairs of valence electrons that are not involved in bonding and are localized on a single atom. In the context of hydrogen bonding, the lone pairs on the oxygen atom of water are essential for forming hydrogen bonds with the hydrogen atom of the hydroxyl group in ethyl alcohol. Recognizing the role of lone pairs helps in visualizing and sketching the hydrogen bonding interactions.