Which of the following has the highest heat of vaporization ?

Options

A. HF
B. HCl
C. HBr
D. Hl

Answer

To determine which of the given substances has the highest heat of vaporization, we can follow these steps:

### Step 1: Understand Heat of Vaporization
Heat of vaporization is the amount of energy required to convert a unit quantity of a substance from liquid to vapor at constant temperature and pressure. Substances with strong intermolecular forces typically have higher heats of vaporization.

**Hint:** Remember that stronger intermolecular forces lead to higher heat of vaporization.

### Step 2: Identify the Substances
In the question, we are given four options (A, B, C, D), which represent different substances. For this solution, we will focus on hydrogen halides, particularly HF.

**Hint:** Look for substances that are known to have strong intermolecular forces.

### Step 3: Analyze Intermolecular Forces
Among the hydrogen halides, HF (hydrogen fluoride) exhibits strong hydrogen bonding due to the highly electronegative fluorine atom. This results in a significant amount of energy being required to break these bonds during the vaporization process.

**Hint:** Consider the type of bonding and intermolecular forces present in each substance.

### Step 4: Compare the Heat of Vaporization
When comparing the heat of vaporization of HF with other hydrogen halides (like HCl, HBr, and HI), HF has the highest heat of vaporization due to its strong hydrogen bonding.

**Hint:** Recall that HF has a unique structure and bonding characteristics compared to other hydrogen halides.

### Step 5: Conclusion
Based on the analysis, we conclude that HF has the highest heat of vaporization among the given options.

**Final Answer:** The substance with the highest heat of vaporization is **Option A: HF**.