Alcohols, phenols, and ethers exhibit distinct physical properties due to their molecular structures and the presence of the hydroxyl (-OH) group. Lower alcohols are typically colorless, toxic liquids with a characteristic sweet smell and burning taste, and they are highly soluble in water due to hydrogen bonding, although solubility decreases with increasing molecular weight. Alcohols generally have higher melting and boiling points compared to their corresponding alkanes because of the hydrogen bonding present in alcohols, which is absent in alkanes. Phenols, which contain a hydroxyl group attached to an aromatic ring, also display similar solubility characteristics and higher boiling points. Ethers, characterized by the ROR structure, are generally less polar than alcohols and phenols, leading to lower boiling points and solubility in water compared to alcohols, but they are still capable of forming hydrogen bonds, albeit to a lesser extent
What is the general solubility trend of alcohols in water?
Lower alcohols are highly soluble in water due to hydrogen bonding, but solubility decreases as the molecular weight increases.
How do the boiling points of alcohols compare to those of alkanes?
Alcohols have higher boiling points than corresponding alkanes because of the presence of hydrogen bonding in alcohols.
Describe the physical state of phenol at room temperature.
Phenol is a colorless, crystalline solid at room temperature with a characteristic phenolic odor.
What happens to the solubility of phenol in water as the temperature increases?
Phenol is sparingly soluble in water at room temperature but becomes completely soluble above 68.5°C.
How do ethers differ from alcohols and phenols in terms of polarity?
Ethers are generally less polar than alcohols and phenols, leading to lower boiling points and solubility in water compared to alcohols.
What is the typical state of lower alcohols at room temperature?
a) Solid
b) Gas
c) Liquid
d) Crystalline
Answer: c) Liquid
Which of the following has the highest boiling point?
a) Methane
b) Ethanol
c) Diethyl ether
d) Propane
Answer: b) Ethanol
What is the melting point of phenol?
a) 0°C
b) 25°C
c) 41°C
d) 100°C
Answer: c) 41°C
How does the solubility of alcohols in water change with increasing molecular weight?
a) Increases
b) Decreases
c) Remains the same
d) Becomes insoluble
Answer: b) Decreases
Which of the following compounds is least soluble in water?
a) Methanol
b) Ethanol
c) Butanol
d) Hexanol
Answer: d) Hexanol