Question 577 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:
\[ P \propto \frac{1}{V} \]
or, more commonly, in equation form:
\[ P_1 V_1 = P_2 V_2 \]
where:
- \( P_1 \) and \( V_1 \) are the initial pressure and volume,
- \( P_2 \) and \( V_2 \) are the final pressure and volume.
**Scenario Analysis:**
In this question, we are told that the pressure of the gas is doubled while the temperature remains constant. Let's denote the initial pressure as \( P_1 \) and the initial volume as \( V_1 \). If the pressure is doubled, we have:
\[ P_2 = 2P_1 \]
Now, we can use Boyle's Law to find the new volume \( V_2 \):
1. **Set up the equation using Boyle's Law:**
\[
P_1 V_1 = P_2 V_2
\]
2. **Substitute \( P_2 \) with \( 2P_1 \):**
\[
P_1 V_1 = (2P_1) V_2
\]
3. **Divide both sides by \( P_1 \) (assuming \( P_1 \neq 0 \)):**
\[
V_1 = 2 V_2
\]
4. **Rearranging gives us:**
\[
V_2 = \frac{V_1}{2}
\]
This shows that when the pressure is doubled, the volume is halved. Thus, 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 Boyle's Law, pressure and volume have an inverse relationship; if one increases, the other must decrease.
- **Option C: The volume remains the same.**
- This option implies that volume does not change with pressure, which is incorrect. Boyle's Law clearly states that volume must change in response to pressure changes when temperature is constant.
- **Option D: The volume quadruples.**
- This option suggests a much larger increase in volume, which is also contrary to Boyle's Law. A quadrupling of volume would imply a significant decrease in pressure, not an increase.
### 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). Remember, Boyle's Law is an inverse relationship.
- **Ignoring Temperature:** Boyle's Law only applies when the temperature is constant. If temperature changes, other gas laws (like Charles's Law) must be considered.
- **Assuming Real Gases Behave Like Ideal Gases:** While Boyle's Law is derived from ideal gas behavior, real gases may deviate from this behavior under high pressure or low temperature.
### 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 correct answer to the question is B: The volume is halved.
- Remember to distinguish between direct and inverse relationships in gas laws.