Which of the following represents the first law of thermodynamics?

Options

A. `q = DeltaU - w`
B. `DeltaH = q + w`
C. `DeltaU = DeltaH + pDeltaV`
D. `DeltaU = pDeltaV`

Answer

To solve the question regarding the representation of the first law of thermodynamics, we can follow these steps:

### Step 1: Understand the First Law of Thermodynamics
The first law of thermodynamics states that the change in internal energy (ΔU) of a system is equal to the heat (Q) added to the system minus the work (W) done by the system. This can be mathematically expressed as:
\[ \Delta U = Q - W \]

### Step 2: Identify the Components
- **ΔU**: Change in internal energy of the system.
- **Q**: Heat added to the system (positive if heat is absorbed, negative if heat is released).
- **W**: Work done by the system (positive if work is done by the system, negative if work is done on the system).

### Step 3: Analyze the Options
If the question provides multiple options, we need to compare them with the equation derived from the first law of thermodynamics. Look for an option that resembles:
\[ \Delta U = Q - W \]
or its rearranged forms.

### Step 4: Conclusion
After analyzing the options, choose the one that correctly represents the first law of thermodynamics.