Question

Pretend that you're talking to a friend who has not yet taken any science courses, and describe how you would explain Boyle's law to her.

Short answer

To explain Boyle's Law to your friend, you can say that it is a rule about how the pressure and volume of a gas are related when the temperature and amount of the gas are constant. It states that when the volume of a gas decreases, its pressure increases and vice versa. Think of a bike tire or balloon; as you pump more air into it, the pressure increases and the volume expands. Similarly, when you squeeze a balloon, the pressure increases and the volume decreases in the squeezed part. In summary, Boyle's Law shows the relationship between the pressure and volume of a gas, and it can be seen in everyday examples like inflating a tire or balloon.

Step-by-step solution

1. Introducing Boyle's Law

Boyle's Law states that when the temperature and amount of a gas are held constant, the pressure of the gas is inversely proportional to its volume. In other words, when the volume of a gas decreases, the pressure increases, and vice versa.

2. Using everyday examples

Consider a bike tire or a balloon; when you pump air into it, you're increasing the pressure inside by increasing the number of air molecules in a fixed space (the tire or balloon). As more air goes into it, the volume increases until it becomes full or stretched. The pressure built-up inside is responsible for providing the firmness and shape of the inflated tire/balloon.

3. Demonstrating the relationship between pressure and volume

Imagine squeezing a partially filled balloon. As you squeeze and reduce its volume, the pressure inside increases because the same number of air molecules are now compressed into a smaller space. This causes the balloon to expand outwards in the areas not being squeezed. This illustrates the inverse relationship between pressure and volume according to Boyle's Law.

4. Further simplification using numbers

Think of a hypothetical gas sample that has a pressure of 2 units and a volume of 4 units. According to Boyle's Law, if we double the pressure (increase it to 4 units), the volume would reduce by half (decrease to 2 units). Similarly, if the pressure is halved (reduced to 1 unit), the volume would double (increased to 8 units).

5. Recap and conclusion

In summary, Boyle's Law states that the pressure and volume of a gas are inversely proportional when temperature and amount of gas are held constant. This means that when the volume of a gas decreases, its pressure increases, and when the volume of a gas increases, its pressure decreases. This is demonstrated through everyday examples like inflating a tire or balloon, or squeezing a partially inflated balloon.