Understandings
Pressure
Equation of state for an ideal gas
Kinetic model of an ideal gas
Mole, molar mass and the Avogadro constant
Differences between real and ideal gases
Applications and Skills
Solving problems using the equation of state for an ideal gas and gas laws
Sketching and interpreting changes of state of an ideal gas on pressure–volume, pressure–temperature and volume–temperature diagrams
Investigating at least one gas law experimentally

Booklet

$$ P = \frac{F}{A}\\ n = \frac NN_a\\ PV = nRT\\ \tilde{E_K}= \frac{3}{2}k_BT = \frac{3}{2}\frac{R}{N_A}T $$

Pressure

Let’s consider a gas molecule confined in a closed box.

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The molecule’s direction is always changing and is it is feeling a force from the walls of the box. By Newton’s third law, the molecule is exerting an equal and opposite force on the walls of the box. We say that the walls of the box feel a pressure P.

More specifically, pressure is defined as the normal force applied per unit area

$$ P = \frac FA $$

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Example 1

Two hollow cubes of side 25 cm with one face missing are placed together at the missing face, as shown on the right. The air inside the solid formed is pumped out.

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Determine the force that is necessary to separate the cubes.

Example 2

  1. A 150 kg man stands on one foot on some ice. Given that his foot is about 9.0 cm by 10 cm in rectangular cross-section, find the pressure on the ice.
  2. If the ice is thin enough that it will break under a pressure of $1.0*10^{5}Pa$, what should be the area of a snowshoe that will just prevent him from breaking through when on one foot?

Mole and Avogadro’s Number

By definition, one mole of any substance contains as many particles as there are atoms in $12 g$ of carbon-12.