Ice and water are placed in a closed container at a pressure of 1 atm and 273.15 K temperature . If pressure of the system is increased by 2 atm keeping temperature constant the correct observation would be

Options

A. The liquid phase disappears completely
B. The amount of ice increases
C. The solid phase (ice) disappears completely
D. Volume of the system increases

Answer

To solve the problem, we need to analyze the effects of increasing pressure on the equilibrium between ice and water at a constant temperature. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Initial Conditions
- Ice and water are in a closed container at 1 atm pressure and 273.15 K (0°C).
- At this temperature, ice and water are in equilibrium.

**Hint:** Remember that at equilibrium, the rates of melting and freezing are equal.

### Step 2: Analyze the Effect of Increasing Pressure
- The pressure of the system is increased by 2 atm, making the total pressure 3 atm.
- According to the ideal gas law (PV = nRT), if the temperature (T) and the number of moles (n) remain constant, an increase in pressure (P) will result in a decrease in volume (V).

**Hint:** Consider how pressure and volume are related in a closed system.

### Step 3: Relate Pressure Change to Phase Change
- Ice (solid) has a greater volume than water (liquid). Therefore, increasing the pressure will favor the phase with a smaller volume, which is water.
- According to Le Chatelier's principle, if a system at equilibrium is subjected to a change in pressure, the equilibrium will shift in the direction that counteracts the change. In this case, it will shift towards the formation of water from ice.

**Hint:** Think about how equilibrium shifts in response to external changes.

### Step 4: Determine the Outcome
- Since the equilibrium shifts towards the liquid phase (water) to reduce the volume, ice will start to melt.
- This means that the amount of ice will decrease as it converts to water.

**Hint:** Focus on what happens to the solid phase when pressure is increased.

### Step 5: Evaluate the Options
- **Option 1:** Liquid phase disappears completely - Incorrect.
- **Option 2:** The amount of ice increases - Incorrect.
- **Option 3:** The solid phase (ice) disappears completely - Correct.
- **Option 4:** The volume of the system increases - Incorrect.

**Hint:** Review each option carefully in light of the analysis.

### Conclusion
The correct observation when the pressure is increased by 2 atm at constant temperature is that the solid phase (ice) disappears completely.

### Final Answer
**The correct observation is that the solid phase (ice) disappears completely (Option 3).**