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What is Charles's Law (gas law)?
Grade Level:
Class 6
Space Technology, EVs, Climate Change, Biotechnology, HealthTech, Robotics, Chemistry, Physics
Definition
What is it?
Charles's Law tells us how the volume of a gas changes with its temperature when the pressure stays the same. It states that as the temperature of a gas increases, its volume also increases, and as the temperature decreases, its volume decreases.
Simple Example
Quick Example
Imagine blowing up a balloon on a hot summer day in Delhi. If you take that same balloon into an air-conditioned room, you might notice it shrinks a little. This is because the cooler temperature makes the air inside the balloon take up less space, showing Charles's Law in action.
Worked Example
Step-by-Step
Let's say a balloon has a volume of 2 Liters (V1) when the temperature is 27 degrees Celsius (T1). What will its new volume (V2) be if the temperature increases to 77 degrees Celsius (T2)?
Step 1: Convert temperatures to Kelvin. T1 = 27 + 273 = 300 K. T2 = 77 + 273 = 350 K.
---Step 2: Write down Charles's Law formula: V1/T1 = V2/T2.
---Step 3: Plug in the known values: 2 L / 300 K = V2 / 350 K.
---Step 4: To find V2, multiply both sides by 350 K: V2 = (2 L / 300 K) * 350 K.
---Step 5: Calculate V2: V2 = (0.00666...) * 350 K = 2.33 Liters.
Answer: The new volume of the balloon will be 2.33 Liters.
Why It Matters
Understanding Charles's Law helps engineers design better engines for cars and rockets, and even helps scientists predict weather patterns. It's crucial for careers in aerospace engineering, climate science, and even in developing new technologies for electric vehicles.
Common Mistakes
MISTAKE: Using Celsius temperatures directly in the formula. | CORRECTION: Always convert Celsius temperatures to Kelvin (add 273) before using them in Charles's Law calculations.
MISTAKE: Confusing Charles's Law with Boyle's Law. | CORRECTION: Charles's Law is about Volume and Temperature (V and T), while Boyle's Law is about Volume and Pressure (V and P). Remember C for Charles and T for Temperature.
MISTAKE: Assuming pressure changes. | CORRECTION: Charles's Law applies only when the pressure of the gas remains constant. If pressure changes, it's a different gas law.
Practice Questions
Try It Yourself
QUESTION: A gas in a container has a volume of 5 Liters at 300 K. If the temperature is lowered to 150 K, what will the new volume be (assuming constant pressure)? | ANSWER: 2.5 Liters
QUESTION: A balloon has a volume of 10 L at 27 degrees Celsius. If its volume expands to 12 L, what is the new temperature in degrees Celsius (assuming constant pressure)? | ANSWER: 87 degrees Celsius
QUESTION: A gas at 20 degrees Celsius occupies 400 mL. What temperature in Kelvin is required to reduce its volume to 300 mL, assuming pressure is constant? | ANSWER: 219.75 K
MCQ
Quick Quiz
Which of these everyday situations best demonstrates Charles's Law?
A pressure cooker whistling loudly
A bicycle tire feeling harder after being left in the sun
A balloon shrinking when moved from a warm room to a cold room
A soda bottle fizzing when opened
The Correct Answer Is:
C
Option C shows that as temperature decreases (cold room), the volume of the gas (air in the balloon) also decreases, which is exactly what Charles's Law states. The other options relate to pressure or gas release.
Real World Connection
In the Real World
Charles's Law is used in hot air balloons! To make a hot air balloon fly, the air inside it is heated. As the temperature of the air increases, its volume expands, making it less dense than the cooler air outside. This difference in density creates lift, allowing the balloon to float up into the sky, just like a lighter object floats on water.
Key Vocabulary
Key Terms
VOLUME: The amount of space a substance occupies | TEMPERATURE: A measure of how hot or cold something is | KELVIN: The standard unit of temperature used in science, where 0 K is absolute zero | CONSTANT: Staying the same; not changing
What's Next
What to Learn Next
Now that you understand how temperature affects gas volume, you're ready to explore Boyle's Law! Boyle's Law will teach you how pressure affects gas volume, helping you understand even more about how gases behave around us.
