When ammonia gas is subjected to sudden expansion from a region of high pressure into a region of low pressure, which of the following changes is expected to take place?

Options

A. decrease in kinetic energy and potential energy
B. conversion of kinetic energy to potential energy
C. conversion of potential energy to kinetic energy
D. increase in kinetic energy and potential energy

Answer

To solve the question regarding the behavior of ammonia gas during sudden expansion from high pressure to low pressure, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Scenario**:
- Ammonia gas is expanding from a region of high pressure to a region of low pressure. This means that the gas is undergoing a rapid change in its environment.

**Hint**: Think about what happens to gas when it expands.

2. **Relate Pressure to Kinetic Energy**:
- The kinetic energy (KE) of gas molecules is related to temperature (T) and pressure (P). According to the equation for kinetic energy of a gas, KE is proportional to temperature, which in turn is directly proportional to pressure (from Gay-Lussac's law).

**Hint**: Recall the relationship between pressure, temperature, and kinetic energy.

3. **Analyze the Effect of Pressure Change**:
- Since the gas is expanding into a region of lower pressure, the pressure experienced by the gas molecules decreases. As pressure decreases, the kinetic energy of the gas molecules also decreases.

**Hint**: Consider how a decrease in pressure affects the motion of gas molecules.

4. **Apply the Conservation of Energy Principle**:
- According to the conservation of energy, if the kinetic energy decreases, there must be a corresponding change in potential energy (PE). Specifically, the decrease in kinetic energy will result in an increase in potential energy.

**Hint**: Remember that energy cannot be created or destroyed, only transformed from one form to another.

5. **Evaluate the Options**:
- Now, let's evaluate the provided options:
- **Option 1**: Decrease in kinetic energy and potential energy - This is incorrect because potential energy must increase if kinetic energy decreases.
- **Option 2**: Conversion of kinetic energy to potential energy - This is correct as we established that a decrease in kinetic energy leads to an increase in potential energy.
- **Option 3**: Conversion of potential energy to kinetic energy - This is incorrect as we are observing the opposite effect.
- **Option 4**: Increase in kinetic energy and potential energy - This is incorrect as kinetic energy is decreasing.

**Hint**: Carefully consider each option in light of the energy transformations discussed.

6. **Conclusion**:
- The correct answer is **Option 2: Conversion of kinetic energy to potential energy**.