6. Thiols are compounds that contain an –SH functional group - Scottish Highers Chemistry - Question 6 - 2019

Propan-1-ol has a higher boiling point than ethanethiol due to stronger hydrogen bonding present in propan-1-ol compared to the permanent dipole-dipole interactions in ethanethiol. When boiling, propan-1-ol requires more energy to break these hydrogen bonds compared to breaking the dipole interactions in ethanethiol.

The thiol that contains only one carbon atom is methanethiol.

To calculate the minimum mass of ethanethiol:

1. Convert volume of air to cm³: 43,900 L = 43,900,000 cm³

2. Calculate the total mass of ethanethiol: Minimum concentration = 2.7 × 10⁻⁷ mg/cm³ Total mass = 43,900,000 cm³ × 2.7 × 10⁻⁷ mg/cm³ = 11.87 mg

Thus, a minimum of 11.87 mg of ethanethiol needs to be present.

2-methyl-2-propanethiol is classified as a tertiary thiol because the thiol group (-SH) is attached to a carbon atom that is connected to three other carbon atoms.

The isomer formed from the addition reaction is 2-methyl-2-propanethiol. It has three carbon atoms connected with the thiol group on the second carbon, having the structure:

       H   H
        |   |
H—C—C—C—H
        |   |
       H   S—H

To find the mass of 2-methyl-2-propanethiol:

1. Theoretical mass = 90 g (GFM from above)
2. Yield = 84%
3. Actual mass produced = 0.84 × 30.5 g = 25.62 g

Thus, the chemist produced approximately 25.62 g of 2-methyl-2-propanethiol.