3.1 Define boiling point - NSC Physical Sciences - Question 3 - 2018 - Paper 2
Question 3
3.1 Define boiling point.
3.2 Write down the:
3.2.1 Name of the FUNCTIONAL GROUP of these compounds.
3.2.2 IUPAC name of compound C.
3.2.3 Structural formula of ... show full transcript
Worked Solution & Example Answer:3.1 Define boiling point - NSC Physical Sciences - Question 3 - 2018 - Paper 2
Step 1
Define boiling point.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Boiling point is defined as the temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid. At this temperature, the liquid transitions to a gaseous state.
Step 2
Write down the FUNCTIONAL GROUP of these compounds.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The functional group for the compounds listed is the carboxyl group (-COOH), which is characteristic of carboxylic acids.
Step 3
IUPAC name of compound C.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The IUPAC name of compound C is propanoic acid.
Step 4
Structural formula of the FUNCTIONAL isomer of compound B.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The structural formula of the functional isomer of compound B (acetic acid) is:
H O
| ||
H-C-C-O-H
|
H
This shows the arrangement of atoms in the isomer.
Step 5
Which ONE of the compounds, A or B or C, has the highest vapor pressure?
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Compound B (CH₃COOH) has the highest vapor pressure because it has the lowest boiling point among the three compounds. Lower boiling points generally correlate with higher vapor pressures due to higher rates of evaporation.
Step 6
Besides the conditions used to determine boiling points, give a reason why this is a fair comparison.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
This is a fair comparison because both compounds B and X are compared under similar conditions of temperature and atmospheric pressure. They also have comparable molecular masses, which helps isolate the effect of their structural differences.
Step 7
Is compound X a PRIMARY, SECONDARY or TERTIARY alcohol? Give a reason for the answer.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Compound X is a PRIMARY alcohol because the hydroxyl (-OH) group is attached to a carbon atom that is bonded to only one other carbon atom.
Step 8
Fully explain the difference between the boiling points by referring to the types of intermolecular forces present in each of these compounds.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The difference between the boiling points of compounds B (CH₃COOH) and X (CH₃CH₂CH₂OH) can be explained by the types of intermolecular forces they exhibit.
Both compounds experience hydrogen bonding due to the presence of hydroxyl groups.
However, compound B (acetic acid) can engage in additional hydrogen bonding due to the presence of its carboxylic acid functional group, which allows it to form dimers.
Conversely, compound X only has one hydrogen bonding site.
Therefore, compound B has stronger intermolecular forces and hence a higher boiling point than compound X.
