Concept:
This problem is solved using the Combined Gas Law, which relates the pressure, volume, and temperature of a fixed amount of gas.
• Combined Gas Law Formula: \( \frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2} \)
• \( P \): Pressure.
• \( V \): Volume.
• \( T \): Absolute temperature (must be in Kelvin).
Step 1: Identifying the initial and final states.
Initial State:
\[ P_1 = P, \quad V_1 = V, \quad T_1 = T \]
Final State (according to conditions):
\[ P_2 = 2P \quad (\text{doubled}) \]
\[ T_2 = T/2 \quad (\text{halved}) \]
Let the new volume be \( V_2 \).
Step 2: Substituting values into the gas law equation.
\[
\frac{P \cdot V}{T} = \frac{(2P) \cdot V_2}{(T/2)}
\]
To simplify the right side, recall that dividing by a fraction is the same as multiplying by its reciprocal:
\[
\frac{PV}{T} = \frac{2P \cdot V_2 \cdot 2}{T} = \frac{4P \cdot V_2}{T}
\]
Step 3: Solving for \( V_2 \).
Cancel \( P \) and \( T \) from both sides of the equation:
\[
V = 4V_2
\]
\[
V_2 = \frac{V}{4}
\]