Boyle’s Law

What are the 4 variables that describe a gas phase system? Volume Temperature Pressure Amount of gas (in moles)

Don’t add or remove any gas. Fixed Mass? You don’t change the number of moles of gas. That is… Don’t add or remove any gas.

BOYLE - 1662 Temperature and Amount are constant. Look at relationship between P and V. What happened when I increased the pressure on the syringe? As pressure increases, volume decreases.

Image From Tiger Boyle’s Law: 4 step J-Tube experiments

Trial Pressure (atm) Volume (cm3) 1 1.00 800 2 2.00 400 3 3.00 267 4 4.00 200

Inverse Relationships Graph of two variables is a ... Properties: Relationship is inverse. Product of the two variables is a constant. hyperbola

Scientists plot data because a picture shows relationships better than lists of numbers. There are lots of “pictures” that scientists & mathematicians recognize.

PressureVolume (atm-cm3) Trial Pressure (atm) Volume (cm3) PressureVolume (atm-cm3) 1 1.00 800 2 2.00 400 3 3.00 267 4 4.00 200 For a given T and amount, pressure X volume always equals the same number – the product is CONSTANT!

Comparison Pressure Change Volume Change Trials 1 & 2 1 to 2 800 to 400 2 to 1 Trials 1 & 3 1 to 3 800 to 267 3 to 1 Trials 1 & 4 1 to 4 800 to 200 4 to 1

Boyle’s Law - words The volume of a sample of gas is inversely proportional to its pressure, at constant temperature.

Boyle’s Law - mathematically P x V = k (constant) V = k/P or P = k/V P1V1 = P2V2 For every point on the hyperbola, P x V = the same constant, k