Properties of alcohols Flashcards
What functional group is present in alcohols?
-OH (hydroxyl group)
The hydroxyl group is responsible for the physical and chemical properties of alcohols.
What is the simplest alcohol and its chemical formula?
Methanol, CH₃OH
Methanol is used as a high-performance fuel and an important chemical feedstock.
What is the primary use of ethanol?
Alcoholic drinks, fuel, solvent, and feedstock
Ethanol is the second member of the alcohol homologous series.
How are alcohols named?
By adding the suffix -ol to the stem name of the longest carbon chain
The position of the alcohol functional group is indicated using a number.
What are the physical property differences between alcohols and alkanes with the same number of carbon atoms?
Less volatile, higher melting points, greater water solubility
These differences diminish as the carbon chain length increases.
What type of bonds do alkanes have?
Non-polar bonds
The electronegativity of hydrogen and carbon is very similar.
What intermolecular forces exist between alkanes?
Weak London forces
These forces are due to the non-polar nature of alkane molecules.
What type of bond is present in alcohols?
Polar O—H bond
The difference in electronegativity between oxygen and hydrogen creates polarity.
What intermolecular forces are present in alcohols?
Hydrogen bonds and weak London forces
Hydrogen bonds are stronger due to the polar O—H groups.
Why do alcohols have lower volatility than alkanes?
Stronger intermolecular hydrogen bonds require more energy to break
This contrasts with the weaker London forces in alkanes.
Why are alcohols like methanol and ethanol soluble in water?
They can form hydrogen bonds with water
Alkanes cannot form hydrogen bonds, making them less soluble.
How does the solubility of longer-chain alcohols compare to hydrocarbons?
Decreases as hydrocarbon chain size increases
The influence of the -OH group becomes relatively smaller.
What classification depends on the number of hydrogen atoms and alkyl groups attached to the carbon with the -OH group?
Primary, secondary, or tertiary alcohols
This classification helps predict reactions with oxidising agents.
What characterizes a primary alcohol?
The -OH group is attached to a carbon with two hydrogen atoms and one alkyl group
Methanol and ethanol are examples of primary alcohols.
What characterizes a secondary alcohol?
The -OH group is attached to a carbon with one hydrogen atom and two alkyl groups
Examples include propan-2-ol and pentan-3-ol.
What characterizes a tertiary alcohol?
The -OH group is attached to a carbon with no hydrogen atoms and three alkyl groups
Examples include 2-methylpropan-2-ol and 2-methylbutan-2-ol.
