Answered

In an experiment, two unknown compounds (one an alcohol and the other an ether) of equal molecular mass were dissolved in water. The result of the experiment is shown in the table.

Solubility Comparison
\begin{tabular}{|l|l|}
\hline
Unknown Compound & Solubility ( [tex]$g / 100 ml$[/tex] water) \\
\hline
A & 7.7 \\
\hline
B & 6.8 \\
\hline
\end{tabular}

Which of the following correctly explains the identity of Compound B and its solubility?

A. It is an alcohol because the lack of hydrogen bonding between the OH-groups makes it less soluble.
B. It is an ether because it is unable to form a hydrogen bond, so it is less soluble than the alcohol.
C. It is an ether because in the absence of a highly electronegative atom like O, F, or N, it lacks hydrogen bonding and is thus less soluble.
D. It is an alcohol because dispersion forces between the OH-group and organic chain make it less soluble.



Answer :

GinnyAnswer
To identify Compound B and explain its solubility, we need to consider the chemical properties of alcohols and ethers, particularly in relation to their solubility in water.

### Step-by-Step Solution:

1. Understanding Solubility:
- Alcohols generally have higher solubility in water compared to ethers of similar molecular mass. This is due to the ability of alcohols to form hydrogen bonds with water molecules.
- Ethers, on the other hand, have lower solubility because they cannot form hydrogen bonds with water as effectively as alcohols do. They do not have a hydroxyl (-OH) group and thus lack the necessary sites to form strong hydrogen bonds with water.

2. Given Data:
- Compound A: Solubility = 7.7 g/100 ml water
- Compound B: Solubility = 6.8 g/100 ml water

3. Comparing Solubilities:
- Compound A (7.7 g/100 ml) is more soluble in water than Compound B (6.8 g/100 ml).
- Since alcohols are typically more soluble in water due to hydrogen bonding, we deduce that Compound A is likely the alcohol and Compound B is likely the ether.

4. Explanation for Compound B:
- Since Compound B has lower solubility (6.8 g/100 ml), it must be the ether because ethers, without the hydroxyl group, cannot form hydrogen bonds as effectively as alcohols, leading to lower solubility in water.

5. Analyzing Statements:
- Statement 1: Incorrect. The presence of the OH group (not the lack) would make a compound more soluble due to hydrogen bonding.
- Statement 2: Correct. It accurately states that ethers are less soluble than alcohols because they cannot form hydrogen bonds.
- Statement 3: Also correct. It explains that ethers lack highly electronegative atoms like O, F, or N (for hydrogen bonding), and hence are less soluble.
- Statement 4: Incorrect. Dispersion forces involving the OH group in alcohols would not typically make it less soluble in water.

### Conclusion:
The correct statement explaining the identity and solubility of Compound B is:
- "It is an ether because in the absence of a highly electronegative atom like O, F, or N, it lacks hydrogen bonding and is thus less soluble." This is the third statement in the list provided. Therefore, the correct answer corresponds to that explanation.