Are alcohols less soluble in water?

Dipole-dipole and hydrogen bond intermolecular forces pull the ethanol molecules apart from one another.

Explanation:

Small alcohols have attached#OH#groups which make the alcohols polar.

The polarity of the alcohol and polarity of the water create intermolecular forces, most notably dipole-dipole forces.

The positive and negative dipoles in the molecules align, tugging at one another and causing the alcohol molecules to break apart from one another in the water and dissolve.

Especially notable in alcohols is the presence of hydrogen bonding, the strongest type of dipole-dipole forces that occurs between a hydrogen atom and either an oxygen, nitrogen, or fluorine atom.

Complete Step By Step Solution:
The $ - OH$ group in alcohols is polar and forms hydrogen bonds with water which results in solubility of alcohols in water. Lower alcohols have less carbon atoms than that of higher alcohols. Higher alcohols have large no. of hydrocarbon chains which results in more steric hindrance to make bonds which result in less solubility. And also with increase of molar mass solubility decreases, which again results in favor of more solubility in case of lower alcohols. And when bulkiness or no. of hydrocarbon chains increases the steric hindrance increases and hence it becomes difficult for higher alcohols to make bonds or react with water. So the solubility of lower alcohols is higher than that of higher alcohols. So the given statement is true.
So the 1st option is correct.

Note:
Always keep in mind that higher the steric hindrance to react or to make bonds, lower will be its tendency to react. So solubility will be less if it is difficult to make bonds.

In case of alcohols, just as it happens in case of many other biological molecules, the basic solubility rule that like dissolves like is a bit more complexed. Each alcohol consists of a carbon chain (always nonpolar) and a OH group (which is polar). For ethanol for example the chemical formula looks lie this: C2H5OH. Ethanol has a 2 carbon chain and a OH group. As water is polar it attracts OH group. Carbon chain on the other hand as nonpolar is repelled. Solubility of alcohols is therefore determined by the stronger of the two forces.

Because of the strength of the attraction of the OH group, first three alcohols (methanol, ethanol and propanol) are completely miscible. They dissolve in water in any amount. Starting with the four-carbon butanol the solubility of alcohols is starting to decrease. After the 7-carbon heptanol, alcohols are considered immiscible. The alcohol solublity in water can be observed below. The amounts are in mol/100g of H2O at 1atm and 25oC.

The viscosity of alcohols increase as the size of the molecules increases. This is because the strength of the intermolecular forces increases, holding the molecules more firmly in place.

Polarity
Amide > Acid > Alcohol > Ketone ~ Aldehyde > Amine > Ester > Ether > Alkane
Amide is the most polar while alkane is the least.
Alcohol is ranked third in terms of polarity due to its hydrogen bonding capabilities and presence of one oxygen atom in an alcohol molecule. Carboxylic acids are more polar than alcohols because there are two oxygen atoms present in a carboxylic acid molecule.

The flammability of alcohols decrease as the size and mass of the molecules increases. Combustion breaks the covalent bonds of the molecules, so as the size and mass of the molecules increases, there are more covalent bonds to break in order to burn that alcohol. Hence, more energy is required to break the bonds, therefore the flammability of alcohols decrease as size and mass of molecules increases.

The following table describes the chemical formula of five alcohols. Which of these alcohols should be the least soluble in water?

Alcohols are organic molecules that contain at least one hydroxy group. This question presents five alcohol molecules that each contain a single hydroxy group. We need to identify the molecule that should be the least soluble in water.

Substances tend to be soluble in one another if both substances exhibit similar intermolecular forces. Water molecules are polar due to the large electronegativity difference between the oxygen and hydrogen atoms. The partial positively charged hydrogen atom of one water molecule experiences a strong electrostatic attraction to the lone pair electrons of an oxygen atom from another water molecule. This strong electrostatic attraction is called hydrogen bonding. Similar to water, the hydroxy group of an alcohol is polar due to the large electronegativity difference between the oxygen and hydrogen atoms. As such, small alcohol molecules, such as methanol, exhibit strong hydrogen bonds with one another.

As methanol and water molecules exhibit similar intermolecular forces, they can form strong hydrogen bonds with one another and the two substances are soluble in each other. All alcohol molecules contain polar hydroxy groups. But not all alcohol molecules are as soluble in water as methanol, and some alcohols are considered insoluble in water.

Let’s consider the alcohol pentan-1-ol. The hydroxy group is polar and could exhibit hydrogen bonding with water molecules. But the long hydrocarbon chain is nonpolar and cannot hydrogen bond. Because the long hydrocarbon chain cannot form hydrogen bonds with water, it is less energetically favorable for the alcohol to dissolve. So pentan-1-ol is less soluble in water than methanol. In general, the solubility of an alcohol in water tends to decrease as the length of the carbon chain increases. So the alcohol that should be the least soluble in water is the alcohol that has the longest carbon chain.

Of the answer choices, the alcohol with the longest carbon chain is pentan-1-ol. So the alcohol that should be the least soluble in water is pentan-1-ol.

Why is alcohol less soluble in water?

Are all alcohols soluble in water?

Which alcohols are not soluble in water?