Which of the following statements is true?[Fill in the blank]

Question

BlackTom AI · Accepted Answer

Hydrogen bonding requires a hydrogen covalently bound to a strongly electronegative atom (commonly O–H or N–H) to act as a hydrogen bond donor, and an electronegative atom with a lone pair (O, N, etc.) to act as a hydrogen bond acceptor.

1) Relevant knowledge points and concepts
- Donor: a hydrogen attached to O or N (e.g., O–H, N–H) can donate an H-bond.
- Acceptor: lone pairs on electronegative atoms (O or N) can accept H-bonds.
- Functional groups considered:
  - Phenol (Ar–OH): has an O–H (donor) and oxygen lone pairs (acceptor).
  - Carboxylic acid (R–COOH): has O–H (donor) and carbonyl O lone pairs (acceptor).
  - Tertiary amine (R3N): has lone pair on N (acceptor) but no N–H (not a donor).
  - Ether (R–O–R): has lone pairs on O (acceptor) but no O–H (not a donor).

2) Step-by-step reasoning
- For option (c): Phenol contains an OH group → can donate H; carboxylic acid contains OH → can donate H. Therefore both can act as hydrogen-bond donors. That satisfies the donor requirement for both species.
- Test other options against definitions:
  - (a) Claims ethers and carboxylic acids are both unable to act as H-bond acceptors. This is false: ethers (lone pairs on O) are acceptors, and carboxylic acids have carbonyl O (and hydroxyl O) that can accept H-bonds.
  - (b) Claims carboxylic acids and tertiary amines can both act as H-bond donors. Carboxylic acids can, but tertiary amines lack N–H, so they cannot donate H-bonds → false.
  - (d) Claims tertiary amines and ethers are both unable to act as H-bond acceptors. Both have lone pairs (N or O) and therefore can act as acceptors → false.

3) Intermediate “checks”
- Phenol: OH present → donor = yes.
- Carboxylic acid: OH present → donor = yes.
- Tertiary amine: no N–H → donor = no.
- Ether: no O–H → donor = no.

4) Why the correct answer is correct
Because both phenols and carboxylic acids possess O–H groups that can donate hydrogen bonds, option (c) correctly identifies two functional groups that are hydrogen-bond donors.

5) Why other choices are incorrect
- (a) Incorrect: ethers and carboxylic acids can accept H-bonds (they have lone pairs).
- (b) Incorrect: tertiary amines cannot donate (no N–H).
- (d) Incorrect: tertiary amines and ethers do have lone pairs and so can act as H-bond acceptors.

6) Conclusion
The correct statement is c. Phenols and carboxylic acids can both act as hydrogen bond donors. This matches the provided answer.

Which of the following statements is true?[Fill in the blank]单项选择题

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Which of the following statement about Hydrogen bonds is correct?

When the molecules of ethanol, C2H5OH, are added to water, the ethanol molecules . 当乙醇分子 C 2 H 5 OH 加入水中时，乙醇分子会。

Which of the following statement about Hydrogen bonds is correct?

Which of the following statement about Hydrogen bonds is correct?

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Which of the following statements is true?[Fill in the blank]单项选择题

类似问题

Alcohols can:[Fill in the blank]

Which of the molecules below would you expect to have the highest boiling point?[Fill in the blank]

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Which of the following statement about Hydrogen bonds is correct?

When the ________ molecules of ethanol, C2H5OH, are added to water, the ethanol molecules ________. 当乙醇________分子 C 2 H 5 OH 加入水中时，乙醇分子会________。

Which of the following statement about Hydrogen bonds is correct?

Which of the following statement about Hydrogen bonds is correct?

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希望你的学习变得更简单

When the molecules of ethanol, C2H5OH, are added to water, the ethanol molecules . 当乙醇分子 C 2 H 5 OH 加入水中时，乙醇分子会。