Question

Difficulty: EasyPneumatics and Gas Laws

A backup breathing canister has a volume of 50 in350 \text{ in}^3 and stores gas at an absolute pressure of 2000 psi2000 \text{ psi}. During a transfer process, the gas is allowed to expand into a larger holding tank, reaching a total final volume of 250 in3250 \text{ in}^3. Assuming the temperature remains constant, what is the new absolute pressure of the gas in psi\text{psi}?

Answer: 400 psi

Answer

400
According to Boyle's Law, the pressure and volume of a gas are inversely proportional when the temperature is constant (P1V1=P2V2P_1V_1 = P_2V_2). Since the volume increased by a factor of 5 (from 50 to 250 cubic inches), the pressure must decrease by a factor of 5. Dividing the initial 2000 psi by 5 gives a final pressure of 400 psi.

Step-by-Step Solution

1
Identify the initial and final states of the gas.
P1=2000 psiP_1 = 2000 \text{ psi}, V1=50 in3V_1 = 50 \text{ in}^3, and V2=250 in3V_2 = 250 \text{ in}^3.
Organizing the known variables is the first step in solving any gas law problem.
2
Apply Boyle's Law to relate pressure and volume.
Equation to use: P1V1=P2V2P_1 V_1 = P_2 V_2.
Boyle's Law states that for a fixed mass of gas at constant temperature, pressure and volume are inversely proportional.
3
Substitute the known values into the equation and solve for the final pressure (P2P_2).
2000×50=P2×2502000 \times 50 = P_2 \times 250, which simplifies to 100000=250P2100000 = 250 P_2. Dividing both sides by 250 gives P2=400P_2 = 400.
This mathematical calculation yields the new absolute pressure after the gas has expanded.

Key Concept

Boyle's Law (Inverse relationship between pressure and volume)

Alternative Method

Instead of full algebraic substitution, recognize the proportionality: the volume increases by a factor of 5 (250/50=5250 / 50 = 5). Because pressure and volume are inversely proportional, the pressure must be divided by 5. Thus, 2000 psi/5=400 psi2000 \text{ psi} / 5 = 400 \text{ psi}.
Estimated Time:45s
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