Question 574 of 949
According to Boyle's Law, what happens to the volume of a gas when the pressure is doubled, assuming the temperature remains constant?
- The volume doubles
- The volume is halved
- The volume remains the same
- The volume quadruples
Correct Answer:
B
Explanation
**Correct Option: B. The volume is halved.**
### Detailed Explanation:
**Understanding Boyle's Law:**
Boyle's Law states that for a given mass of an ideal gas at constant temperature, the pressure (P) of the gas is inversely proportional to its volume (V). This relationship can be mathematically expressed as:
\[ P \times V = k \]
where \( k \) is a constant for a given amount of gas at a constant temperature. This means that if the pressure increases, the volume must decrease, and vice versa, as long as the temperature remains constant.
**Step-by-Step Analysis:**
1. **Initial Conditions:** Let's assume we have a gas with an initial pressure \( P_1 \) and an initial volume \( V_1 \). According to Boyle's Law, we can write:
\[ P_1 \times V_1 = k \]
2. **Doubling the Pressure:** If the pressure is doubled, we have:
\[ P_2 = 2P_1 \]
3. **Finding the New Volume:** We need to find the new volume \( V_2 \) when the pressure is doubled. Using Boyle's Law again:
\[ P_2 \times V_2 = k \]
Substituting \( P_2 \) into the equation gives:
\[ (2P_1) \times V_2 = k \]
4. **Setting the Equations Equal:** Since \( k \) is constant, we can set the two equations equal to each other:
\[ P_1 \times V_1 = (2P_1) \times V_2 \]
5. **Solving for \( V_2 \):** Dividing both sides by \( P_1 \) (assuming \( P_1 \neq 0 \)):
\[ V_1 = 2 \times V_2 \]
Rearranging gives:
\[ V_2 = \frac{V_1}{2} \]
This shows that when the pressure is doubled, the volume is halved, confirming that the correct answer is **B. The volume is halved.**
### Why Other Options Are Incorrect:
- **Option A: The volume doubles.**
- This option suggests that if pressure increases, volume also increases, which contradicts Boyle's Law. According to the law, pressure and volume have an inverse relationship.
- **Option C: The volume remains the same.**
- This option implies that changes in pressure do not affect volume, which is incorrect. Boyle's Law clearly states that volume changes in response to pressure changes when temperature is constant.
- **Option D: The volume quadruples.**
- This option also contradicts Boyle's Law. If the pressure increases, the volume cannot increase; it must decrease. A quadrupling of volume would imply a significant decrease in pressure, which is not the case here.
### Common Pitfalls:
- **Confusing Direct and Inverse Relationships:** Students often confuse direct relationships (where both variables increase or decrease together) with inverse relationships (where one variable increases while the other decreases).
- **Ignoring Temperature:** Boyle's Law only applies when temperature is constant. If temperature changes, the relationship between pressure and volume is not simply described by Boyle's Law.
### Revision Summary:
- Boyle's Law states that pressure and volume of a gas are inversely related at constant temperature.
- Doubling the pressure of a gas results in halving its volume.
- The formula \( P_1 \times V_1 = P_2 \times V_2 \) is key to solving problems related to Boyle's Law.
- Always remember that temperature must remain constant for Boyle's Law to apply.