Consider the organic compounds represented by the letters A to C below - NSC Physical Sciences - Question 2 - 2016 - Paper 2

The IUPAC name of compound A is 2-methylbutane.

The structural formula of a tertiary alcohol that is a structural isomer of compound B is:

         H   H   H
         |   |   |
     H - C - C - C
         |   |   |
         H   C - OH
         |   |   |
         H   H   H

The concentrated sulphuric acid acts as a catalyst and increases the rate of reaction, facilitating the esterification process.

The inorganic product formed is water (H₂O).

To find the empirical formula, we first calculate the moles of each element based on the percentages:

• For Hydrogen (H):

$n(H) = \frac{6.67}{1} = 6.67 ext{ moles}$

• For Carbon (C):

$n(C) = \frac{40}{12} = 3.33 ext{ moles}$

• For Oxygen (O):

$n(O) = \frac{53.33}{16} = 3.33 ext{ moles}$

The ratio of H:C:O is 6.67:3.33:3.33, which simplifies to:

$H_2C_O$,

resulting in the empirical formula of CH₂O.

To find the molecular formula, we know the molar mass of the ester is 60 g·mol⁻¹. The empirical formula mass is:

• C (12 g/mol) × 1 = 12 g/mol
• H (1 g/mol) × 2 = 2 g/mol
• O (16 g/mol) × 1 = 16 g/mol

Thus:

$12 + 2 + 16 = 30 ext{ g/mol}$

To find the factor: 60 g/mol ÷ 30 g/mol = 2. Therefore, the molecular formula is:

$C_2H_4O_2$.

The structural formula of methanoic acid (formic acid) is:

    O
    ||
H - C - OH

The IUPAC name of the ester formed from the alcohol and methanoic acid is methyl methanoate.