A sample of liquid in a thermally insulated container is stirred for 1hr by a mechanical attachment to a motor in the surroundings, which of the following thermodynamic quantity for the system is zero

Options

A. Work (W)
B. Change in internal energy `(DeltaE)`
C. Change in enthalpy `(Delta H)`
D. None of these

Explanation

To solve the question, we need to analyze the situation described and apply the principles of thermodynamics. Here’s a step-by-step breakdown:

### Step 1: Understand the System
The problem states that we have a sample of liquid in a thermally insulated container. This means that the system (the liquid) does not exchange heat with its surroundings.

**Hint:** Remember that a thermally insulated container implies no heat transfer, which means \( Q = 0 \).

### Step 2: Identify Heat Transfer
Since the container is thermally insulated, there is no heat exchange with the surroundings. Therefore, the heat transfer \( Q \) for the system is zero.

**Hint:** In thermodynamics, \( Q \) represents heat transfer. If the system is insulated, what can you conclude about \( Q \)?

### Step 3: Consider Work Done
The liquid is being stirred by a mechanical attachment (motor). This means that work is being done on the system. The work done on the system is not zero; rather, it contributes to the internal energy of the liquid.

**Hint:** Work done on the system can change its internal energy. Think about how stirring affects the energy of the liquid.

### Step 4: Apply the First Law of Thermodynamics
According to the first law of thermodynamics, the change in internal energy (\( \Delta E \)) of a system is given by:
\[ \Delta E = Q + W \]
Since \( Q = 0 \) (no heat transfer), we have:
\[ \Delta E = W \]
This means that the change in internal energy is equal to the work done on the system.

**Hint:** The first law of thermodynamics relates internal energy, heat, and work. If one of these is zero, how does that affect the others?

### Step 5: Analyze Enthalpy Change
Enthalpy change (\( \Delta H \)) is not necessarily zero in this scenario. Enthalpy can change due to work done on the system, especially when there are changes in temperature or pressure. In this case, since the liquid is being stirred, it is likely that the temperature of the liquid will increase, indicating that \( \Delta H \) is not zero.

**Hint:** Enthalpy is related to internal energy and can change even if heat transfer is zero. Consider how stirring affects temperature.

### Conclusion
From the analysis, we conclude that the thermodynamic quantity that is zero for the system is the heat transfer \( Q \). The correct answer to the question is that \( Q = 0 \).

**Final Answer:** The thermodynamic quantity that is zero is \( Q \) (heat transfer).