Define the term boiling point - NSC Physical Sciences - Question 3 - 2017 - Paper 2
Question 3
Define the term boiling point.
What property of alcohols requires them to be heated in a water bath?
The boiling points of the alcohols are compared with each othe... show full transcript
Worked Solution & Example Answer:Define the term boiling point - NSC Physical Sciences - Question 3 - 2017 - Paper 2
Step 1
Define the term 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
The boiling point is defined as the temperature at which the vapor pressure of a liquid equals the external atmospheric pressure. At this point, the liquid turns into vapor.
Step 2
What property of alcohols requires them to be heated in a water bath?
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
Alcohols are flammable and volatile, which is why they are heated in a water bath to ensure safety and control over the heating process.
Step 3
What structural requirements must the alcohols meet to make it a fair comparison?
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 alcohols must be straight-chain primary alcohols, ensuring they have similar molecular characteristics for a valid comparison.
Step 4
Fully explain the trend in the boiling points.
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 trend in boiling points can be largely attributed to increasing molecular weight and the associated increase in van der Waals forces. As the chain length increases (from butan-1-ol to hexan-1-ol), the boiling point increases due to stronger intermolecular forces that require more energy to overcome.
Step 5
How will the boiling point of hexan-1-ol be affected if the volume of hexan-1-ol used is doubled? Choose from INCREASES, DECREASES or REMAINS THE SAME.
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
Remains the same.
Step 6
Write down the independent variable for this 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
The independent variable is the type of alcohol being tested (hexan-1-ol and hexanal).
Step 7
Fully explain this observation.
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
The boiling point of hexan-1-ol is higher than that of hexanal due to the presence of stronger intermolecular dipole-dipole forces in hexan-1-ol compared to hexanal, which primarily experiences weaker dispersion forces. The functional group influences the intermolecular forces significantly, resulting in a higher boiling point for hexan-1-ol.
