DP Chemistry (first assessment 2025)
Question 19M.1A.SL.TZ1.9
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.1A.SL.TZ1.9 |
| Level | SL | Paper | 1A | Time zone | TZ1 |
| Command term | Question number | 9 | Adapted from | N/A |
9.
[Maximum mark: 1]
19M.1A.SL.TZ1.9
What is the order of increasing boiling point?
A. CH3CH2CH2CH3 < CH3CH(OH)CH3 < CH3COCH3 < CH3CO2H
B. CH3CH2CH2CH3 < CH3COCH3 < CH3CH(OH)CH3 < CH3CO2H
C. CH3CO2H < CH3COCH3 < CH3CH(OH)CH3 < CH3CH2CH2CH3
D. CH3CH2CH2CH3 < CH3COCH3 < CH3CO2H < CH3CH(OH)CH3
[1]
Markscheme
B
Examiners report
Ranking compounds in order of increasing boiling point proved challenging. There existed a number of misconceptions based on the incorrect answers chosen being close to evenly distributed.
Syllabus sections
Structure 2. Models of bonding and structure » Structure 2.2—The covalent model » Structure 2.2.9—Given comparable molar mass, the relative strengths of intermolecular forces are generally: London (dispersion) forces < dipole–dipole forces < hydrogen bonding. Explain the physical properties of covalent substances to include volatility, electrical conductivity and solubility in terms of their structure.