For the compounds listed above, write down the following: 3.1.1 Structural formula of compound F 3.1.2 LETTER that represents a POSITIONAL isomer of compound E 3.1.3 LETTER that represents a CHAIN isomer of compound E The boiling points increase from compound A to compound D - NSC Physical Sciences - Question 3 - 2017 - Paper 2

The letter that represents a positional isomer of compound E (butan-1-ol) is D (butan-2-ol). This is because the hydroxyl group (-OH) is located on the second carbon instead of the first carbon.

The letter that represents a chain isomer of compound E (butan-1-ol) is G (2-methylpropan-1-ol), as it differs in the carbon chain arrangement.

The increase in boiling points from compound A (Methanol) to compound D (Butan-1-ol) can be attributed to the increase in molecular size and weight. As the number of carbon atoms increases, the overall van der Waals forces (dispersion forces) also increase, leading to higher boiling points.

The intermolecular forces responsible for this increase are London dispersion forces. These forces become stronger with increased molecular surface area and mass.

The boiling point represented by Y is 108 °C.

I arrived at the conclusion that Y corresponds to 108 °C by analyzing the trend of boiling points in the table. As we observe the boiling points of the known compounds, 85 °C (for methanol), 108 °C (for compound F), and 122 °C (for 2-methylpropan-2-ol), it indicates a progression, allowing me to conclude that the missing boiling point Y must be 108 °C.

The two structural formulas for compound A (Methanol) can be drawn as follows:

    H   H
     |   |
H - C - O - H
     |   
    H 

And the alternate representation:

      H
      |
   H - C - O - H
      |
      H

The dotted line (which represents hydrogen bonding) can be shown between two separate methanol molecules:

H - O - H .......... H - O - H
      |                     |
      H                   H

This illustrates the hydrogen bonding interaction between methanol molecules.

The reaction that occurs between compound B and propanoic acid in the presence of concentrated sulfuric acid is an Esterification reaction.

The structural formula of the organic product formed from the esterification reaction can be represented as follows:

     O
      ||
 R - C - O - R'

Where R represents the hydrocarbon chain from propanoic acid and R' represents the hydrocarbon chain from compound B.