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What is Charles's Law (volume-temperature relationship)?
Grade Level:
Class 7
Space Technology, EVs, Climate Change, Biotechnology, HealthTech, Robotics, Chemistry, Physics
Definition
What is it?
Charles's Law describes how the volume of a gas changes with its temperature when the pressure stays the same. It states that if you increase the temperature of a gas, its volume will also increase, and if you decrease the temperature, its volume will decrease.
Simple Example
Quick Example
Imagine you have a balloon in your hand. If you take this balloon out into the hot afternoon sun during summer, it will get slightly bigger. This is because the air inside the balloon gets warmer, and according to Charles's Law, its volume increases.
Worked Example
Step-by-Step
Let's say you have a gas in a container with a volume of 200 mL at a temperature of 27 degrees Celsius. If you heat the gas to 127 degrees Celsius, what will its new volume be? (Remember to convert Celsius to Kelvin by adding 273). --- Step 1: Convert initial temperature to Kelvin. T1 = 27 + 273 = 300 K. --- Step 2: Convert final temperature to Kelvin. T2 = 127 + 273 = 400 K. --- Step 3: Write down the known values. V1 = 200 mL, T1 = 300 K, T2 = 400 K. We need to find V2. --- Step 4: Use Charles's Law formula: V1/T1 = V2/T2. --- Step 5: Plug in the values: 200 mL / 300 K = V2 / 400 K. --- Step 6: Solve for V2. V2 = (200 mL * 400 K) / 300 K. --- Step 7: Calculate V2 = 80000 / 300 = 266.67 mL. --- The new volume of the gas will be approximately 266.67 mL.
Why It Matters
Charles's Law helps engineers design spacecraft and hot air balloons, understanding how gases behave in extreme temperatures. It's crucial for scientists working on climate change models and developing new technologies like advanced car engines, making it a foundation for careers in aerospace, engineering, and environmental science.
Common Mistakes
MISTAKE: Using Celsius temperatures directly in the formula | CORRECTION: Always convert Celsius temperatures to Kelvin (by adding 273) before using them in Charles's Law calculations.
MISTAKE: Confusing the relationship – thinking volume decreases with increasing temperature | CORRECTION: Remember that volume and temperature are directly proportional; if one increases, the other increases, assuming constant pressure.
MISTAKE: Forgetting that pressure must remain constant for Charles's Law to apply | CORRECTION: Always assume or confirm that the pressure of the gas is not changing when applying Charles's Law.
Practice Questions
Try It Yourself
QUESTION: A balloon contains 5 liters of air at 300 K. If the temperature is increased to 450 K, what will be the new volume of the balloon (assuming constant pressure)? | ANSWER: 7.5 liters
QUESTION: A gas occupies 100 mL at 27 degrees Celsius. What will be its volume if the temperature is lowered to -73 degrees Celsius (at constant pressure)? | ANSWER: 66.67 mL (approx)
QUESTION: A gas sample has a volume of 600 mL at 50 degrees Celsius. To what temperature (in degrees Celsius) must the gas be cooled for its volume to become 400 mL, assuming pressure remains constant? | ANSWER: -41 degrees Celsius (approx)
MCQ
Quick Quiz
Which of the following describes the relationship between volume and temperature in Charles's Law?
They are inversely proportional
They are directly proportional
They have no relationship
Volume increases as temperature decreases
The Correct Answer Is:
B
Charles's Law states that as temperature increases, volume also increases (and vice versa) when pressure is constant. This is a direct proportionality.
Real World Connection
In the Real World
You can see Charles's Law in action every time a hot air balloon takes off. The air inside the balloon is heated, causing its volume to expand and become less dense than the cooler air outside, allowing the balloon to float. This principle is also used in weather balloons that carry instruments high into the atmosphere.
Key Vocabulary
Key Terms
Volume: The amount of space a substance occupies | Temperature: A measure of the hotness or coldness of a substance | Kelvin: An absolute temperature scale used in scientific calculations | Directly Proportional: When two quantities change in the same direction (both increase or both decrease)
What's Next
What to Learn Next
Great job learning about Charles's Law! Next, you should explore Boyle's Law, which explains the relationship between the volume and pressure of a gas. Understanding both will give you a complete picture of how gases behave under different conditions.
