Define and adiabatic process and state two essential conditios for such a process to take place.

Answer

### Step-by-Step Solution:

1. **Definition of an Adiabatic Process**:
An adiabatic process is defined as a thermodynamic process in which there is no heat transfer (Q) between the system and its surroundings. This means that the system is perfectly insulated, and any change in the internal energy of the system is solely due to work done on or by the system.

2. **First Essential Condition**:
The first essential condition for an adiabatic process to occur is that the heat transfer (Q) must be zero. This implies that the system does not exchange heat with its surroundings during the process. Mathematically, this can be expressed as:
\[ \Delta Q = 0 \]

3. **Second Essential Condition**:
The second essential condition is that the process must occur rapidly. This rapidity ensures that there is not enough time for heat exchange to take place between the system and its surroundings. In practical terms, this means that the system must be insulated or the boundary of the system must be such that it prevents heat transfer.

4. **Conclusion**:
To summarize, an adiabatic process is characterized by no heat transfer (Q = 0) and must occur rapidly to maintain the conditions necessary for it to be classified as adiabatic.