What is Boyle's Law? | Simple Explanation for Class 6

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What is Boyle's Law (gas law)?

Grade Level:

Class 6

Space Technology, EVs, Climate Change, Biotechnology, HealthTech, Robotics, Chemistry, Physics

Definition

What is it?

Boyle's Law tells us how the pressure and volume of a gas are related when its temperature stays constant. It states that for a fixed amount of gas, if you increase the pressure, its volume will decrease, and if you decrease the pressure, its volume will increase.

Simple Example

Quick Example

Imagine you have an air pump for your bicycle tyre. When you push down the handle (increasing pressure), the air inside the pump gets squeezed into a smaller space (decreasing volume). This is Boyle's Law in action – more pressure means less space for the air.

Worked Example

Step-by-Step

PROBLEM: A gas has a volume of 10 litres at a pressure of 2 atmospheres. If the pressure is increased to 4 atmospheres, what will be the new volume of the gas (assuming temperature is constant)?
---STEP 1: Identify the given values.
Initial Volume (V1) = 10 litres
Initial Pressure (P1) = 2 atmospheres
Final Pressure (P2) = 4 atmospheres
New Volume (V2) = ?
---STEP 2: Recall Boyle's Law formula: P1 * V1 = P2 * V2
---STEP 3: Substitute the known values into the formula.
2 atmospheres * 10 litres = 4 atmospheres * V2
---STEP 4: Calculate the left side of the equation.
20 = 4 * V2
---STEP 5: Solve for V2.
V2 = 20 / 4
V2 = 5 litres
---ANSWER: The new volume of the gas will be 5 litres.

Why It Matters

Understanding Boyle's Law is super important for engineers designing everything from space rockets to air conditioners. It helps in developing safe diving equipment, understanding how our lungs work, and even improving the efficiency of engines in Electric Vehicles (EVs).

Common Mistakes

MISTAKE: Thinking that if pressure increases, volume also increases. | CORRECTION: Remember, pressure and volume have an inverse relationship. If one goes up, the other goes down.

MISTAKE: Forgetting that Boyle's Law only applies when temperature is kept constant. | CORRECTION: Always check if the problem states that temperature is constant. If not, other gas laws might apply.

MISTAKE: Not using consistent units for pressure or volume. | CORRECTION: Make sure both pressure values are in the same unit (e.g., atmospheres, Pascals) and both volume values are in the same unit (e.g., litres, cubic meters) before solving.

Practice Questions

Try It Yourself

QUESTION: A gas occupies 20 litres at a pressure of 1 atmosphere. If the pressure is doubled, what is the new volume? | ANSWER: 10 litres

QUESTION: A balloon contains 5 litres of air at a pressure of 3 atm. If the pressure is reduced to 1.5 atm, what will be the new volume of the balloon? | ANSWER: 10 litres

QUESTION: A gas sample has a volume of 150 mL at a pressure of 760 mmHg. If the volume is compressed to 100 mL, what is the new pressure in mmHg? | ANSWER: 1140 mmHg

MCQ

Quick Quiz

According to Boyle's Law, if the pressure on a gas increases while its temperature remains constant, what happens to its volume?

It increases

It decreases

It remains the same

It first increases then decreases

The Correct Answer Is:

Boyle's Law states that pressure and volume are inversely proportional. This means if pressure goes up, volume must go down, assuming temperature is constant.

Real World Connection

In the Real World

Scuba divers use Boyle's Law every time they go underwater. As they dive deeper, the pressure around them increases, which causes the air in their lungs and dive tanks to compress (volume decreases). They need to understand this to manage their air supply and avoid health risks when ascending.

Key Vocabulary

Key Terms

PRESSURE: The force exerted by gas particles on the walls of their container | VOLUME: The amount of space a gas occupies | INVERSELY PROPORTIONAL: When one quantity increases, the other decreases proportionally | CONSTANT TEMPERATURE: The temperature does not change during the process

What's Next

What to Learn Next

Great job learning about Boyle's Law! Next, you can explore Charles's Law, which explains how temperature affects gas volume, or Gay-Lussac's Law, which talks about pressure and temperature. These will help you understand gases even better!