Which one of the following compounds can be used to distinguish propane from propene?

Options

A. (a) Aqueous `KMnO_(4)`
B. (b) Dil. `H_(2)SO_(4)`
C. (c) `Br_(2) -H_(2)O`
D. (d) Ammoniacal `AgNO_(3)`

Answer

To distinguish propane from propene, we can utilize the following compounds: aqueous KMnO4, dilute H2SO4, and bromine water. Here’s a step-by-step explanation of how each compound can be used for this purpose:

### Step 1: Understanding the Structures
- **Propane (C3H8)**: This is a saturated hydrocarbon, meaning it contains only single bonds between carbon atoms.
- **Propene (C3H6)**: This is an unsaturated hydrocarbon, containing a carbon-carbon double bond.

### Step 2: Using Aqueous KMnO4
- **Reaction**: Aqueous KMnO4 is known for its ability to perform syn-dihydroxylation on alkenes.
- **Observation**: When KMnO4 reacts with propene, the purple color of the solution changes to brown due to the formation of MnO2 and a diol. However, propane does not react with KMnO4, and the purple color remains unchanged.
- **Conclusion**: Aqueous KMnO4 can distinguish propene from propane because it reacts with propene but not with propane.

### Step 3: Using Dilute H2SO4
- **Reaction**: Dilute H2SO4 reacts with alkenes but not with alkanes.
- **Observation**: Propene reacts with dilute H2SO4 to form an alkyl hydrogen sulfate, while propane does not react and remains insoluble.
- **Conclusion**: Dilute H2SO4 can also distinguish propene from propane, as it reacts with propene but not with propane.

### Step 4: Using Bromine Water
- **Reaction**: Bromine water is used to test for unsaturation in compounds.
- **Observation**: When bromine water is added to propene, it decolorizes the brown solution, indicating the presence of a double bond. Conversely, when bromine water is added to propane, the solution remains brown.
- **Conclusion**: Bromine water can distinguish propene from propane since it decolorizes with propene but not with propane.

### Step 5: Using Ammoniacal Silver Nitrate (Tollens' Reagent)
- **Reaction**: Ammoniacal silver nitrate (Tollens' reagent) is used to oxidize aldehydes but does not react with alkenes or alkanes.
- **Observation**: Both propane and propene do not react with Tollens' reagent.
- **Conclusion**: Ammoniacal silver nitrate cannot be used to distinguish between propane and propene since it does not react with either.

### Final Answer
The compounds that can be used to distinguish propane from propene are:
1. Aqueous KMnO4
2. Dilute H2SO4
3. Bromine water