Question at position 9 The vapor pressure of four different substances at 20 °C is given in the table. [table]
Substance | Vapor Pressure (mmHg) A | 0.0012 B | 18 C | 175 D | 442
[/table] Which statement is correct? The intermolecular forces between C molecules should be weaker than those between B molecules.The normal boiling point of substance D should be greater than that of substance B.Substance A has the lowest boiling pointThe intermolecular forces between B molecules should be stronger than those between A molecules.

Question

Question at position 9 The vapor pressure of four different substances at 20 °C is given in the table. [table]
Substance | Vapor Pressure (mmHg) A | 0.0012 B | 18 C | 175 D | 442
[/table] Which statement is correct? The intermolecular forces between C molecules should be weaker than those between B molecules.The normal boiling point of substance D should be greater than that of substance B.Substance A has the lowest boiling pointThe intermolecular forces between B molecules should be stronger than those between A molecules.

BlackTom AI · Accepted Answer

Higher vapor pressure at the same temperature indicates greater volatility, which implies weaker intermolecular forces and a lower boiling point.

Relevant concepts: vapor pressure measures how readily molecules escape the liquid; stronger intermolecular forces (IMFs) reduce vapor pressure. The normal boiling point is the temperature where vapor pressure equals 760 mmHg; a substance with a higher vapor pressure at 20 °C needs less heating to reach 760 mmHg, so it has a lower normal boiling point.

Step-by-step reasoning with the given data (all at 20 °C):
- Vapor pressures: A = 0.0012 mmHg, B = 18 mmHg, C = 175 mmHg, D = 442 mmHg.
- Rank from lowest to highest vapor pressure: A < B < C < D.
- Corresponding IMF strength (inverse relationship): A has the strongest IMFs, then B, then C, and D has the weakest IMFs.
- Corresponding volatility/boiling behavior: A is least volatile (highest boiling point), D is most volatile (lowest boiling point).

Intermediate comparisons:
- Compare C and B: C (175 mmHg) has a much higher vapor pressure than B (18 mmHg) at the same temperature, so C’s molecules escape more easily. Therefore IMFs between C molecules are weaker than those between B molecules.
- Normal boiling point of D vs B: D has a higher vapor pressure at 20 °C (442 mmHg) than B (18 mmHg), so D will reach 760 mmHg at a lower temperature than B. Thus D’s normal boiling point is lower than B’s, so the statement claiming it is greater is incorrect.
- Substance A’s vapor pressure is the lowest (0.0012 mmHg), so A has the highest—not lowest—boiling point; the statement that “A has the lowest boiling point” is wrong.
- The statement “IMFs between B molecules should be stronger than those between A molecules” is reversed: A’s IMFs are stronger than B’s.

Why the correct answer is correct: C’s much higher vapor pressure compared with B directly indicates weaker intermolecular forces in C than in B.

Final confirmation: The correct answer is "The intermolecular forces between C molecules should be weaker than those between B molecules."

类似问题

Which intermolecular interactions contribute most to the water solubility of organic compounds? A. ionic interactions and dispersion forces B. hydrogen bonding and ion-dipole interactions C. dispersion forces and hydrogen bonding D. dipole-dipole interactions and dispersion forces

Which intermolecular interactions contribute most to the water solubility of organic compounds? A. ionic interactions and dispersion forces B. hydrogen bonding and ion-dipole interactions C. dispersion forces and hydrogen bonding D. dipole-dipole interactions and dispersion forces

Question at position 3 Which of the following intermolecular forces is/are demonstrated by pure CH3F? Choose the single best answer. 1. hydrogen bonding 2. ionic forces 3. dispersion forces 4. dipole-dipole forces 3 only1 only2 and 4 only3 and 4 only4 only2 only1 and 3 only1 and 2 only

Match the following 1: Halogen bonding is 2: Van der Waals interactions are caused by the 3: Dipolar interactions result 4: The cation-π interaction is a

Which of the following is incorrect about intermolecular forces?[Fill in the blank]

What type of bonding interactions are possible at positions (i) O-H and (iii) N+, respectively, of the following drug?

What type of bonding interactions are possible at positions (i) O-H and (iii) N+, respectively, of the following drug?

Which intermolecular interactions contribute most to the water solubility of drugs?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单

类似问题

Which intermolecular interactions contribute most to the water solubility of organic compounds? A. ionic interactions and dispersion forces B. hydrogen bonding and ion-dipole interactions C. dispersion forces and hydrogen bonding D. dipole-dipole interactions and dispersion forces

Which intermolecular interactions contribute most to the water solubility of organic compounds? A. ionic interactions and dispersion forces B. hydrogen bonding and ion-dipole interactions C. dispersion forces and hydrogen bonding D. dipole-dipole interactions and dispersion forces

Question at position 3 Which of the following intermolecular forces is/are demonstrated by pure CH3F? Choose the single best answer. 1. hydrogen bonding 2. ionic forces 3. dispersion forces 4. dipole-dipole forces 3 only1 only2 and 4 only3 and 4 only4 only2 only1 and 3 only1 and 2 only

Match the following 1: Halogen bonding is ____ 2: Van der Waals interactions are caused by the ____ 3: Dipolar interactions result ____ 4: The cation-π interaction is a ____

Which of the following is incorrect about intermolecular forces?[Fill in the blank]

What type of bonding interactions are possible at positions (i) O-H and (iii) N+, respectively, of the following drug?

What type of bonding interactions are possible at positions (i) O-H and (iii) N+, respectively, of the following drug?

Which intermolecular interactions contribute most to the water solubility of drugs?

更多留学生实用工具

希望你的学习变得更简单

Match the following 1: Halogen bonding is 2: Van der Waals interactions are caused by the 3: Dipolar interactions result 4: The cation-π interaction is a