Total number of hydrogen molecules required to form ethane from ethyne is

Options

A. One
B. Two
C. Three
D. Four

Answer

To determine the total number of hydrogen molecules required to form ethane from ethyne, we can follow these steps:

### Step 1: Write the chemical equation for the reaction.
The reaction of ethyne (C2H2) converting to ethane (C2H6) can be represented as:
\[ \text{C}_2\text{H}_2 + \text{H}_2 \rightarrow \text{C}_2\text{H}_6 \]

### Step 2: Identify the bonds in ethyne.
Ethyne (C2H2) has a triple bond between the two carbon atoms. This triple bond consists of one sigma bond and two pi bonds.

### Step 3: Understand the saturation process.
To convert ethyne to ethane, we need to saturate the triple bond. Each pi bond requires one molecule of hydrogen (H2) to be saturated.

### Step 4: Calculate the number of hydrogen molecules needed.
Since ethyne has two pi bonds, we need:
- 1 H2 molecule for the first pi bond
- 1 H2 molecule for the second pi bond

Thus, the total number of hydrogen molecules required is:
\[ 2 \text{ H}_2 \text{ molecules} \]

### Conclusion
The total number of hydrogen molecules required to form ethane from ethyne is **2**.

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