Dimethyl ether when heated with exces HI gives :

Options

A. `CH_(3)I` and `CH_(3)OH`
B. `CH_(3)I` and `H_(2)O`
C. `C_(2)H_(6)+CH_(3)I `and `CH_(3)OH`
D. `CH_(3)I` and `HCHO`

Answer

To solve the problem of what dimethyl ether gives when heated with excess HI, we can follow these steps:

### Step 1: Identify the structure of dimethyl ether
Dimethyl ether has the molecular formula CH3OCH3. It consists of two methyl groups (CH3) connected by an oxygen atom.

### Step 2: Understand the reaction with HI
When dimethyl ether (CH3OCH3) is heated with hydrogen iodide (HI), it undergoes a cleavage reaction. In normal conditions, the reaction produces methyl iodide (CH3I) and methanol (CH3OH).

### Step 3: Consider the effect of excess HI
In the presence of excess HI, the methanol produced can further react with HI. The reaction can be summarized as follows:

1. **First Reaction**:
\[ CH3OCH3 + HI \rightarrow CH3I + CH3OH \]

2. **Second Reaction** (with excess HI):
\[ CH3OH + HI \rightarrow CH3I + H2O \]

### Step 4: Combine the reactions
When we combine these reactions, we see that the methanol produced in the first reaction reacts with excess HI to yield more methyl iodide and water. Therefore, we can summarize the overall reaction as:

\[ CH3OCH3 + 2HI \rightarrow 2CH3I + H2O \]

### Step 5: Identify the final products
From the overall reaction, we can conclude that the products of heating dimethyl ether with excess HI are:
- Methyl iodide (CH3I)
- Water (H2O)

### Conclusion
Thus, the final answer to the question is that dimethyl ether when heated with excess HI gives **2 CH3I and H2O**.

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