Final answer:
Butanol, due to hydrogen bonding in its structure, has a higher boiling point than hydrocarbons of similar size and is therefore a liquid at -40°C, which is above its melting point and below its boiling point.
Step-by-step explanation:
The question to determine whether butanol is a liquid or a solid at -40°C can be answered by understanding its physical properties, especially its boiling and melting points. Analyzing the molecular structure of butanol, we notice the hydrogen bonding present in alcohols, which significantly raises the boiling point compared to hydrocarbons of similar size.
1-Butanol, which has four carbon atoms and an -OH group, has a higher boiling point than butane due to the presence of hydrogen bonding between molecules, which requires more energy to break. Considering isopropyl alcohol, which is an alcohol with a lower number of carbon atoms and has a melting point of -89°C and a boiling point of 82.5°C, we can infer that 1-butanol will also be a liquid at temperatures well above its melting point but below its boiling point.
Therefore, we can conclude that butanol is a liquid at -40°C, as this is above its expected melting point but below its boiling point.